UMC Announces Share Buy-Back Program

Taipei, Taiwan, R.O.C. – February 15, 2006 - United Microelectronics Corporation (TAIEX: 2303, NYSE: UMC), today held a meeting of the Board of Directors and Supervisors, at which the Board passed a resolution to repurchase 1,000 million shares from the open market. This is the tenth share buy-back program announced by the company. The details for the share buy-back program are as follows:

1. Purpose of the share repurchase: buy back and write off
2. Scheduled period for the repurchase: 2006/02/16~2006/04/15
3. Number of shares to be repurchased: 1,000,000,000 shares
4. Repurchase price range: NT$12.35 to NT$27.50. If the market price falls below the lowest range, the company is still authorized to purchase the shares.
5. The shares will be purchased directly from the open market.
6. The number of shares to be repurchased is 5.05% of the total issued shares of the company.
7. The company currently holds 942,067,000 shares of its stock.

About UMC
UMC (NYSE: UMC, TSE: 2303) is a leading global semiconductor foundry that manufactures advanced process ICs for applications spanning every major sector of the semiconductor industry. UMC delivers cutting-edge foundry technologies that enable sophisticated system-on-chip (SoC) designs, including volume production 90nm, industry-leading 65nm, and mixed signal/RFCMOS. UMC’s 10 wafer manufacturing facilities include two advanced 300mm fabs; Fab 12A in Taiwan and Singapore-based Fab 12i are both in volume production for a variety of customer products. The company employs approximately 12,000 people worldwide and has offices in Taiwan, Japan, Singapore, Europe, and the United States. UMC can be found on the web at http://www.umc.com.