EXHIBIT 11 BOSTON BIOMEDICA, INC. AND SUBSIDIARIES STATEMENT RE COMPUTATION OF INCOME PER SHARE WEIGHTED AVERAGE SHARES Quarter Ended March 31, ---------------------------------- 1997 1996 --------------- ----------------- Average common stock outstanding 4,380,024 2,560,417 Net effect of dilutive common stock equivalents-based on treasury stock method using average market price 445,558 - Issuance of "cheap stock" - 4,357 --------------- ----------------- 4,825,582 2,564,774 =============== ================= Net income (loss) $ 147,758 $ (96,539) =============== ================= Net income (loss) per share 0.03 (0.04) =============== ================= 13