Platelet 3H-imipramine binding was investigated in 8 patients affected by bulimia according to DSM III criteria, and in 7 healthy volunteers. The Bmax +/- SD (fmol/mg protein) was 356 +/- 53 in patients, and 1144 +/- 134 in controls. The Kd +/- SD (nM) was 1.35 +/- 0.44 in patients, and 1.90 +/- 0.72 in controls. There was a significant difference (p less than 0.0001) in Bmax values in the two groups, whereas no significant difference was observed in Kd values. This study suggests the possible involvement of the indoleamine system in bulimia.