6-K

FORM 6-K

U.S. SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16 UNDER THE

SECURITIES EXCHANGE ACT OF 1934

Dated September 22, 2008

Commission File Number 1-14878

GERDAU S.A.

(Exact Name as Specified in its Charter)

N/A (Translation of Registrant’s Name)

Av. Farrapos 1811

Porto Alegre, Rio Grande do Sul - Brazil CEP 90220-005

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F.

Form 20-F x Form 40-F ¨

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): ¨

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): ¨

Indicate by check mark whether by furnishing the information contained in this Form, the registrant is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes ¨ No x

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): Not applicable.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused the Report to be signed on its behalf by the undersigned, thereunto duly authorized.

Date:  September 22, 2008

GERDAU S.A.
By:	/s/Osvaldo Burgos Schirmer
Name: Osvaldo Burgos Schirmer
Title: Chief Financial Officer

EXHIBIT INDEX

Exhibit	Description of Exhibit
99.1	Press release, September 11, 2008.

EX-99.1

Exhibit 99.1

PRESS RELEASE

GERDAU S.A. (Bovespa: GGBR; NYSE: GGB; Latibex: XGGB), pursuant to CVM Instruction 358 of January 3, 2002, hereby informs that its subsidiary Sipar Gerdau, located in Rosário, Argentina, has announced today a US$ 524 million investment plan to increase its capacity.

As a result of this program, Sipar Gerdau will have capability to produce crude steel and will boost existing output of rolled products by around four times. The company’s new installations will be equipped with state-of-the-art technology and will obey the highest quality standards. The new facility will be located in Perez, in the province of Santa Fé, 5km from its current facilities. Construction will take place in two stages, beginning within the next few months.

In the first stage the company will invest US$ 310 million to reach an annual production capacity of 650 thousand tonnes of crude steel and 710 thousand tonnes of rolled products. This stage is expected to be concluded in 2011. In the second stage, the investment will be US$ 214 million to bring each, crude and rolled steel capacities, to 1.1 million tonnes. This phase is expected to be concluded by 2016.

This is a key investment for Gerdau’s positioning in Argentina and will prove crucial in meeting growing demand in the country’s market.

The project will also have a positive economic impact for the region since it will create one thousand jobs during the construction phase and an additional three thousand jobs when it becomes operational.

Rio de Janeiro, September 11, 2008

Osvaldo Burgos Schirmer

Executive Vice President

and Investor Relations Director