Mean plasma levels of beta-endorphin (beta EP), beta-lipotropin (beta LPH) and ACTH were significantly higher in 22 patients with primary affective disorders (PAD) and in 2 schizoaffective subjects off therapy since 10 days than in 22 age- and sex-matched healthy controls. Desimipramine therapy (50-100 mg/day per os for 3-5 weeks) induced in parallel psychological improvement and fall in beta LPH-beta EP in 6 of 8 PAD patients treated, and a normalization of beta EP-beta LPH levels with minimal mood improvement in the 2 schizoaffective subjects. These results indicate that the opioid levels are increased in PAD and schizoaffective patients and normalized by the desimipramine therapy in those patients in whom the affective disorders improved.