EXHIBIT 11 AMERICAN HOME PRODUCTS CORPORATION AND SUBSIDIARIES COMPUTATION OF EARNINGS PER SHARE (In Thousands Except Per Share Amounts) Three Months Ended Nine Months Ended September 30, September 30, 1997 1997 1. Net Income .................. $435,532 $1,471,301 2. Reported earnings per share: a. Average number of common shares outstanding during the period .............. 649,009 645,716 b. Reported earnings per share (1/2a) ............. $0.67 $2.28 3. Primary earnings per share: a. Average number of common shares outstanding during the period ............... 649,009 645,716 b. Common shares deemed outstanding from the assumed exercise of stock options reduced by the number of common shares purchased with the proceeds (determined using the average market price during the period).................... 15,557 14,446 c. Deferred contingent common stock awards .............. 494 494 d. Shares for primary earnings per share calculation (3a+3b+3c) ................ 665,060 660,656 e. Primary earnings per share (1/3d)..................... $0.65 $2.23 4. Fully diluted earnings per share: a. Average number of common shares outstanding during the period................. 649,009 645,716 b. Common shares deemed outstanding from the assumed exercise of stock options reduced by the number of common shares purchased with the proceeds (determined using the higher of the average market price during the period or the market price at the end of the period) ......... 15,557 15,191 c. Deferred contingent common stock awards ............... 494 494 d. Shares for fully diluted earnings per share calculation (4a+4b+4c)...... 665,060 661,401 e. Fully diluted earnings per share (1/4d) ............... $0.65 $2.22 </TABLE)