The free fatty acid content of sound cacao beans of nine geographic orgins varied from 2.7 to 4.8 meq./100 g fat. Fungi grown on cacao beans under humid environmental conditions have remarkable lipolytic activity. Values as high as 200 meq. free acid/100 g fat were obtained for badly deteriorated samples. Titration of the free fatty acids of cacao fat is suggested as a simple control procedure for detecting cocao butter obtained from moldy beans. Percentage composition of the free fatty acid fraction changes as a result of mold growth. Stearic and palmitic acid increased while oleic and linoleic acids decreased. Tracer experiments show no observable conversion of oleic acid to stearic. The changes suggest oxidative reactions to form carbonyl compounds.