As filed with the Securities and Exchange Commission on November 5, 1999
Registration No. 333-

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM S-3
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933


ADVANCED ENERGY INDUSTRIES, INC.
(Exact name of registrant as specified in its charter)

           DELAWARE                                          84-0846841
(State or other jurisdiction of                             (IRS Employer
 incorporation or organization                         Identification Number)

                             1625 SHARP POINT DRIVE
                          FORT COLLINS, COLORADO 80525
                                 (970) 221-4670

(Address, including zip code, and telephone number,
including area code, or registrant's principal
executive offices)

RICHARD P. BECK
ADVANCED ENERGY INDUSTRIES, INC.
1625 SHARP POINT DRIVE
FORT COLLINS, COLORADO 80525
(970) 221-4670

(Name, address, including zip code, and telephone number, including area
code, of agent for service)


                                WITH COPIES TO:

          JAY L. MARGULIES                             BARRY L. DASTIN
         CARISSA C. W. COZE                            RUSS A. CASHDAN
      THELEN REID & PRIEST LLP           KAYE, SCHOLER, FIERMAN, HAYS & HANDLER, LLP
 TWO EMBARCADERO CENTER, SUITE 2100         1999 AVENUE OF THE STARS, SUITE 1600
SAN FRANCISCO, CALIFORNIA  94111-3995          LOS ANGELES, CALIFORNIA  90067


Approximate date of commencement of proposed sale to the public: AS SOON
AS PRACTICABLE AFTER THE EFFECTIVE DATE OF THIS REGISTRATION STATEMENT.


If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box. [ ]

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box. [ ]

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. [ X ] Registration No. 333-87455

If this Form is a post-effective amendment pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. [ ]

If the delivery of the prospectus is expected to be made pursuant to Rule 434, please check the following box. [ ]




                                               CALCULATION OF REGISTRATION FEE
====================================================================================================================================
                                                             PROPOSED MAXIMUM
 TITLE OF EACH CLASS OF SECURITIES       AMOUNT TO BE         OFFERING PRICE     PROPOSED MAXIMUM AGGREGATE           AMOUNT OF
          TO BE REGISTERED                REGISTERED             PER UNIT              OFFERING PRICE(1)            REGISTRATION FEE
------------------------------------------------------------------------------------------------------------------------------------
5 1/4% Convertible Subordinated
Notes due 2006.................          $20,000,000               100%                   $20,000,000                  $5,560
------------------------------------------------------------------------------------------------------------------------------------
Common Stock, $0.001
par value......................              (2)                    0                          0                         (3)
====================================================================================================================================

(1) Estimated solely for the purpose of calculating the registration fee pursuant to Rule 457(a) under the Securities Act of 1933, as amended.

(2) Includes 403,796 shares of common stock initially issuable upon conversion of the convertible notes at the rate of 20.1898 shares of common stock per $1,000 principal amount of convertible notes. Pursuant to Rule 416 under the Securities Act, such number of shares of common stock registered hereby shall also include an indeterminate number of additional shares of common stock that may be issued from time to time upon conversion of the convertible notes by reason of adjustment of the conversion price in certain circumstances.

(3) Pursuant to Rule 457(i) under the Securities Act, there is no filing fee with respect to the shares of common stock issuable upon conversion of the convertible notes, because no additional consideration will be received in connection with the exercise of the conversion privilege.



INCORPORATION BY REFERENCE

This registration statement is being filed by Advanced Energy Industries, Inc., a Delaware corporation (the "Company"), to register $20 million principal amount of 5 1/4% convertible subordinated notes due 2006 ("Notes"), in accordance with Rule 462(b) under the Securities Act. The Company filed an earlier registration statement on Form S-3 (File No. 333-87455) relating to the offering by the Company of up to $115 million principal amount of Notes, which registration statement was declared effective on November 4, 1999. The contents of such earlier registration statement are incorporated by reference in this registration statement.

EXHIBITS

Exhibit           Description
-------           -----------
5.1               Opinion of Thelen Reid & Priest LLP re Legality of the Notes

8.1               Opinion of Thelen Reid & Priest LLP re Tax Matters

23.1              Consents of Thelen Reid & Priest LLP (included in Exhibits 5.1 and 8.1)

23.2              Consent of Arthur Andersen LLP

23.3              Consent of KPMG LLP

24.1              Power of Attorney (previously filed as an exhibit to the Company's
                  Registration Statement on Form S-3 (File No. 333-87455))


1

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Fort Collins, State of Colorado, on November 5, 1999.

Advanced Energy Industries, Inc.

By:   /s/ Richard P. Beck
   -----------------------------------------------------
Name: Richard P. Beck
     ---------------------------------------------------
Title: Senior Vice President and Chief Financial Officer
      --------------------------------------------------

Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed by the following persons in the capacities and on the date indicated.

                                                   *
                                                   ---------------------------
Date: November 5, 1999                             Douglas S. Schatz
                                                   President and Chief
                                                   Executive Officer and
                                                   Chairman of the Board
                                                   (Principal Executive Officer)


                                                   /s/ Richard P. Beck
                                                   ---------------------------
Date: November 5, 1999                             Richard P. Beck
                                                   Senior Vice President and
                                                   Chief Financial Officer and
                                                   Director
                                                   (Principal Financial and
                                                   Accounting Officer)


                                                   *
                                                   ---------------------------
Date: November 5, 1999                             G. Brent Backman
                                                   Director


                                                   *
                                                   ---------------------------
Date: November 5, 1999                             Hollis Caswell
                                                   Director

2

                                                   *
                                                   ---------------------------
Date: November 5, 1999                             Arthur A. Noeth
                                                   Director

                                                   *
                                                   ---------------------------
Date: November 5, 1999                             Elwood Spedden
                                                   Director


                                                   *
                                                   ---------------------------
Date: November 5, 1999                             Gerald Starek
                                                   Director


                                                   *
                                                   ---------------------------
Date: November 5, 1999                             Arthur Zafiropoulo
                                                   Director


* By: /s/ Richard P. Beck
     ---------------------------
      Richard P. Beck
      Attorney-in-Fact

3

EXHIBIT INDEX

EXHIBIT  DESCRIPTION
-------  -----------
5.1      Opinion of Thelen Reid & Priest LLP re Legality of the Notes

8.1      Opinion of Thelen Reid & Priest LLP re Tax Matters

23.1     Consents of Thelen Reid & Priest LLP (included in Exhibits 5.1 and 8.1)

23.2     Consent of Arthur Andersen LLP

23.3     Consent of KPMG LLP

24.1     Power of Attorney (previously filed as an exhibit to the Company's
         Registration Statement on Form S-3 (File No. 333-87455))


November 4, 1999

Advanced Energy Industries, Inc.
1625 Sharp Point Drive
Fort Collins, CO 80525

Ladies and Gentlemen:

We have acted as counsel for Advanced Energy Industries, Inc., a Delaware corporation (the "Company"), in connection with the preparation of the Registration Statement on Form S-3 (as may be amended or supplemented, the "Form S-3"), relating to the issuance and sale by the Company of up to $20,000,000 of convertible subordinated notes (the "Notes") and the issuance of common stock, $0.001 par value, of the Company ("Common Stock") on conversion of the Notes. The Form S-3 was filed by the Company in reliance on Rule 462(b) under the Securities Act of 1933, as amended, and incorporates by reference the contents of the Registration Statement on Form S-3 (File No. 333-87455), as amended, previously filed by the Company.

In so acting, we have examined the Form S-3, the Company's Certificate of Incorporation and Bylaws, as in effect as of the date hereof, the form of underwriting agreement relating to the Notes (the "Underwriting Agreement"), the form of Indenture relating to the Notes (the "Indenture"), and such other documents, records, certificates of officers of the Company, certificates of public officials and other instruments as we have deemed necessary or appropriate under the circumstances for purpose of giving the opinion expressed herein. In making such examinations, we have assumed (a) the genuineness of all signatures; (b) the authenticity of all documents submitted to us as originals; (c) the conformity to original documents of all documents submitted to us as certified copies or photocopies; and (d) the identity and capacity of all individuals acting or purporting to act as public officials.

Based upon, subject to and limited by the foregoing, we are of the opinion that:

(1) The Notes, when issued in accordance with the Underwriting Agreement and executed and authenticated in accordance with the Indenture, will be valid and legally binding obligations of the Company, enforceable against the Company in accordance with their terms, except as may be limited by (a) applicable bankruptcy, insolvency, reorganization, moratorium or similar laws relating to or affecting the enforcement of creditors' rights generally, including without limitation laws relating to fraudulent transfers or conveyances, preferences and


Advanced Energy Industries, Inc.
November 4, 1999

Page 2

equitable subordination; (b) general principles of equity, including without limitation, concepts of materiality, reasonableness, good faith and fair dealing (regardless of whether considered in a proceeding in equity or at law); and (c) the unenforceability under certain circumstances of provisions purporting to release or exculpate any party from liability for its acts or omissions, or purporting to impose a duty upon any party to indemnify any other party when any claimed damages result from the negligence, gross negligence or willful misconduct of the party seeking such indemnity.

(2) The Common Stock issuable upon conversion of the Notes, when issued upon such conversion in accordance with the terms of the Notes, will be legally issued, fully paid and non-assessable.

In giving the foregoing opinions, we have assumed that (a) the Notes are duly authenticated by the Trustee and duly executed and delivered on behalf of the Company against payment therefor in accordance with the terms approved by the Board of Directors of the Company and in accordance with the terms of the Underwriting Agreement and the Indenture, (b) the Board of Directors of the Company, or the duly authorized committee thereof does not change its determination that tender of the Notes to be converted constitutes adequate consideration for the issuance of the Common Stock, (c) the Board of Directors of the Company duly authorizes the issuance of the Common Stock,
(d) the consideration for the issuance of the Common Stock is at least equal to the aggregate par value of the Common Stock, (e) the Form S-3 is effective as of the time of the sale, and (f) the Company actually receives the price for the Notes and the consideration for the Common Stock that is approved by the Board of Directors or duly authorized committee.

We are members of the bar of the State of New York and we express no opinion as to the laws of any state or jurisdiction other than federal laws of the United States, the laws of the State of New York and the corporate laws of the State of Delaware.


Advanced Energy Industries, Inc.
November 4, 1999

Page 3

We hereby consent to the filing of this opinion with the Securities and Exchange Commission as an exhibit to the Form S-3. We further consent to the use of our name under the heading "Legal Matters" in the prospectus incorporated by reference in the Form S-3.

Very truly yours,

/s/ Thelen Reid & Priest LLP

THELEN REID & PRIEST LLP

MLJ/DM/SHK/CCWC/TJM


November 4, 1999

Advanced Energy Industries, Inc.
1625 Sharp Point Drive
Fort Collins, CO 80525

Ladies and Gentlemen:

We have acted as counsel for Advanced Energy Industries, Inc., a Delaware corporation (the "Company"), in connection with the preparation of the Registration Statement on Form S-3 (as may be amended or supplemented, the "Registration Statement"), relating to the issuance and sale by the Company of up to $20,000,000 of convertible subordinated notes (the "Notes") and the issuance of common stock, $0.001 par value, of the Company ("Common Stock") on conversion of the Notes. The Registration Statement was filed by the Company in reliance on Rule 462(b) under the Securities Act of 1933, as amended, and incorporates by reference the contents of the Registration Statement on Form S-3 (File No. 333-87455), as amended, filed by the Company.

You have requested our opinion with respect to the accuracy of the discussions included or incorporated by reference in the Registration Statement under the heading "Material United States Federal Income Tax Consequences."

In our capacity as counsel for the Company, we have been furnished with and have examined originals or copies, certified or otherwise identified to our satisfaction, of such records of the Company, agreements and other instruments, certificates of officers and representative of the Company, certificates of public officials and other documents as we have deemed necessary to require as a basis for the opinion hereinafter expressed. In making such examinations, we have assumed (i) the genuineness of all signatures; (ii) the authenticity of all documents submitted to us as originals; (iii) the conformity to original documents of all documents submitted to us as certified copies or photocopies; (iv) the identity and capacity of all individuals acting or purporting to act as public officials;
(v) that all representations and statements set forth in the documents submitted to us are true and correct; and (vi) that all obligations imposed by any of the documents submitted to us are enforceable in accordance with their terms.

We have also made such investigations and have reviewed such other documents as we have deemed necessary or appropriate under the circumstances, and have made such


Advanced Energy Industries, Inc.
November 4, 1999

Page 2

examinations of law as we have deemed appropriate for purpose of giving the opinions expressed herein.

Based on the foregoing, we are of the following opinion:

The statements concerning United States taxation set forth in the Registration Statement under the heading "Material United States Federal Income Tax Consequences," to the extent that such statements represent matters of law or legal conclusions, describe the material United States federal income tax consequences expected to result to a holder of Notes and/or Common Stock, subject, however, to the limitations set forth in the Registration Statement, including that the statements apply only to Notes and/or Common Stock held as capital assets, and do not purport to address all aspects of federal income taxation or all tax considerations that may be relevant to all categories of potential purchasers.

Our opinion is based on the Internal Revenue Code of 1986, as amended, applicable Treasury regulations thereunder, and judicial authority and administrative rulings and practices now in effect. Changes to any of the foregoing authorities after the date of the Registration Statement could apply on a retroactive basis and affect the consequences described in the Registration Statement.

We hereby consent to the filing of this opinion with the Securities and Exchange Commission as an exhibit to the Registration Statement. We further consent to the use of our name under the heading "Legal Matters" in the prospectus incorporated by reference in the Registration Statement.

Very truly yours,

/s/ Thelen Reid & Priest LLP

THELEN REID & PRIEST LLP

JRB/JMM


Exhibit 23.2

ARTHUR ANDERSEN LLP

CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS

As independent public accountants, we hereby consent to the incorporation by reference in this Registration Statement on Form S-3 of our report dated February 5, 1999 included in Advanced Energy Industries, Inc's Form 10-K for the year ended December 31, 1998 and to all references to our Firm included in this Registration Statement (File No. 333- ).

                                       /s/ Arthur Andersen LLP


Denver, Colorado
 November 4, 1999


EXHIBIT 23.3

CONSENT OF INDEPENDENT CERTIFIED PUBLIC ACCOUNTANTS

To the Board of Directors
Advanced Energy Industries, Inc.:

We consent to the incorporation by reference in the Registration Statement on Form S-3 of Advanced Energy Industries, Inc. of our report dated January 16, 1998 with respect to the consolidated balance sheets of RF Power Products, Inc. as of November 30, 1997 and 1996 and the related consolidated statements of income, changes in shareholders' equity and cash flows for the years then ended and related schedule (not separately presented herein), which report appears in the annual report on Form 10-K of Advanced Energy Industries, Inc. for the year ended December 31, 1998.

/S/ KPMG LLP

Philadelphia, Pennsylvania
November 4, 1999