A method for the detection and estimation of aflatoxin B1 in green coffee beans is described. According to the AOAC method, the toxin is extracted with aqueous methanol: hexane and the extract is cleaned up on a Celite column. The extract is further purified on a Florisil column and is then chromatographed on thin layer plates. The estimated limit of detection of the method is 2 μg aflatoxin/kg green coffee. About 75% aflatoxin B1 added to green coffee was recovered. The method was used in a survey of suspect samples of green coffee. No aflatoxin was detected in 58 samples originating in 10 producing countries. Preliminary studies with a new extraction solvent (dimethyl sulfoxide:benzene, 30:50) and a Florisil cleanup appear promising. About 85% aflatoxin B1 added to green coffee was recovered.