Describes a 22-yr-old male suffering from chronic severe obsessive-compulsive neurosis (OCN) complicated by frequent depressive episodes. S did not respond to combinations of electroconvulsive shock therapy (ECT) and chlomipramine (150 mg/day) nor to ECT, chlopromazine (200 mg/day), and chlomipramine (225 mg/day). Administering the monoamine oxidase inhibitor, phenelzine (45 mg/day), and chlopromazine (30 mg/day) led to complete alleviation of depression in 10 wks, and 3 wks later the OCN had improved. Relapse occurred after discontinuance.