In a double-blind trial, 146 depressed patients were allocated at random to treatment with the same daily dose (100 mg to 150 mg) of trazodone administered either as divided doses twice daily or as a single dose at night. Over the trial period of 6 weeks there was a highly significant reduction in the mean Hamilton Depression Rating Scale scores in both treatment groups, with no significant differences between them. The patients completed 10 visual analogue scales concerned with their depressive symptomatology, sleep patterns and daytime sequelae. Significant improvement was recorded on all items in both groups, the only significant between-group difference being in relation to how tired the patient felt during the day, which was significantly better on night-time dosage at Weeks 1 and 2. The most significant finding of the study was in relation to the sleep questionnaires completed by the patients on awakening and again in the evening. Trazodone administered as a single dose at night or when given in twice daily divided dosage, improved sleep. During the first week this effect was significantly better for the single dose at night group. This early effect may be particularly useful in providing psychological encouragement to depressed patients at the onset of treatment.