A prospective randomised comparative study on the effectiveness of psychiatric day treatment and inpatient treatment is described. The target population consisted of patients who would normally have been admitted to an open inpatient unit. Outcome indicators were psychopathology, social functioning, interpersonal functioning, social network and social support.

No differences in effectiveness were found between the two forms of treatment, although more patients accepted and completed day treatment, and day patients were more sstisfied. Although a uniform treatment programme for both departments was established, distinct differences did arise in the actual treatment programme offered to the patients. The duration of treatment for the day patients was considerably longer, whilst the intensity of treatment was more low-key. No striking differences in the amount of mediation prescribed and in the occurrence of crisis situations (including suicide) were found.

Day treatment turns out to be a realistic alternative for 33% of all patients admitted for inpatient treatment. It was not possible to predict which type of patient in particular is suitable for day treatment.