These experiments were undertaken to determine the suitability of a flavor-aversion-conditioning paradigm for detecting the effects of trimethyltin and triethyltin. Both organotins produced flavor aversions whose magnitude depended jointly on the dosage administered and the number of flavor-organotin pairings. Estimated ED 50s (for triethyltin, 1.8 mg/kg; for trimethyltin, 3.1 mg/kg) were smaller than the dosages reported to affect other classes of behavior, but nevertheless represented a substantial percentage (25-45%) of the respective published LD-50 values. Flavor-aversion conditioning may represent a valuable tool for studying the effects of organic and inorganic heavy metals.