We studied the effect of acute tryptophan (TRP) depletion in a group of eight abstinent bulimic (BN) subjects and in 12 healthy female controls. Despite being free of episodes of binge-eating and vomiting for a prolonged period, the abstinent BN subjects still appeared to practice dietary restrain as judged by their food intake in a test meal. In addition, their plasma TRP concentrations were significantly lower than those of the controls. Administration of a TRP-free amino acid load (52 g) significantly lowered plasma total and free TRP. However, compared to a balanced amino acid load, this procedure did not have significant effects on mood, appetite or food intake in either the abstinent BN subjects or the healthy controls.