Taipei, R.O.C. -December 9, 2008-United Microelectronics Corporation - (NYSE: UMC; TAIEX: 2303), (UMC) today revised downward its 4Q08 guidance and reported unaudited net sales for the month of November 2008.

Due to weak semiconductor demand resulting from the global economic recession and wafer shipments being pushed-out, UMC announces that it has revised downward its fourth quarter 2008 guidance, originally disclosed on October 29th, 2008. UMC now expects its fourth-quarter revenue to be between NT$18.2 billion and NT$18.7 billion, with 4Q 2008 gross profit margin to be between 7% and 9%. UMC maintains that profits from operations will be positive for overall 2008.

UMC began publishing annual corporate environmental reports (CER) in 2000. In 2006, UMC evolved its CER into CSR to include the company's efforts and achievements in environmental protection, corporate governance and social events participation. GRI introduced its G3 Sustainability Reporting Guidelines in October 2006, and UMC's next CSR report that was released in 2007 earned GRI's highest grade. The Level A grade demonstrates UMC's determination to be considered an international leader in the CSR field.

(*) All figures in thousands of New Taiwan Dollars (NT$), except for percentages.

Additional information about UMC is available on the web at http://www.umc.com.