A simple procedure was devised for the routine screening of aflatoxin B 1 (AFB 1 ) in peanut butter using enzyme-linked immunosorbent assay (ELISA). Peanut butter samples (5 g) were artificially contaminated with AFB 1 and extracted by blending with 25 ml of 55% methanol and 10 ml of hexane. The extract was filtered and aqueous filtrate analyzed by a direct competitive ELISA. Recovery of AFB 1 added to peanut butter samples ranged from 85 to 112%, with an average inter-well coefficient of variation of 18.4%. The inter-assay coefficient of variation was 22.7%. Using this procedure, only 3 of 63 commercial samples of peanut butter had detectable levels (>5.0 μg/kg) of AFB 1 .