Exhibit Volume Page 1 of 55 Millipore Corporation Exhibit 11 Computation of Earnings Per Share (In Thousands Except Per Share Data) Years Ended December 31, Calculation of shares: 1997 1996 1995 Weighted average of shares outstanding during the year used in calculation of earnings per 43,527 (a) 43,602 (a) 44,985 (a) share - Basic Shares outstanding from assumed exercise of stock 2,968 2,801 3,103 option (Treasury Method) (1,757) (1,494) (1,736) (NQ tax benefit) (423) (452) (465) Weighted average of shares outstanding during the year used in calculation of earnings per 44,315 44,457 (b) 45,887 (b) share-Diluted Net Income $ (38,784) $ 43,622 $85,354 Earnings per common share - $ (0.89) $ 1.00 $ 1.90 Basic Earnings per common share - $ (0.89) (c) $ 0.98 $ 1.86 Diluted (a) Represents weighted average of shares outstanding used in the basic earnings per share calculations. (b) Represents weighted average of shares outstanding used in the diluted earnings per share calculations for 1996 and 1996. Common stock equivalents for 1996 and 1995 were included in the weighted average share computation as required by SFAS No. 128. (c) For 1997 basic and diluted earnings per share are the same as the Company was in a loss position.