In recent years, psychiatric institutions have been increasingly urged to justify their clinical policies in order to ensure both effective treatment and efficient management. Assessment instruments for effectiveness and costs are essential to respond to these needs. The aim of this study was to determine the cost-effectiveness of treatments for major depressive disorders. We conducted a comparative pilot investigation of treatment costs in patients with a major depressive episode assigned to specialised out-patient crisis intervention, to specialised in-patient treatment and to standard mental hospital care. The study included 122 subjects. The inclusion criteron was a diagnosis of DSM-III-R major depressive episode. Costs were assessed by determining the average cost for each treatment and the modalities of payment systems. Treatment duration and costs were high, but specialised crisis intervention may considerably reduce the duration of hospitalisation and its associated costs. The average costs of treating major depression were about 4 times greater in the specialised hospital unit than in the standard hospital unit and the crisis intervention centre. The burden of payment was comparatively higher for the state and reduced for insurance companies when the treatment of major depressive disorders involved less in-patient care.