Costs of the admission replacing day-treatment (experimental condition) during first and second year of the follow-up are compared to those of standard hospitalization, including ambulatory and extramural care. Day treatment appeared to be feasible in a satisfactory degree for 38% of the admission population. Only direct treatment costs are considered here. Controls and experimentals did not differ statistically significant with respect to total treatment costst in either year. But there was a significant difference concerning cost of ambulatory care only: experimentals had about twice as many contacts as ordinary clinical patients. This effect still continued during the second year of the follow-up. It was concluded that particularly for patients who could be treated in a day hospital setting, the alternative to ordinary clinical care was cost-effective. This result corresponds with recent studies on community care in Londen (Muijen et al. 1990) and on day care in Manchester (Creed et al. 1990).