Before this study, a randomized controlled trial in a Dutch university psychiatric ward showed that 33% of all admitted patients were suited for day-treatment soon after admission. It was also demonstrated that, for this patiens, full-time and day treatment had the same effect on patient functioning. In this study it was shown that these results are applicable to all Dutch open psychiatric wards of general hospitals, despite some differences in patientcharacteristics and lenght of treatment. For this purpose, 160 representative patients were examined soon after admission. Using the percentage of 33%, the division between beds and places for day-treatment could change from the 1989 figure of 1:5 into 1:1. However, ward psychiatrists judged only 13% of all admitted patients suited for day-treatment. Using this percentage, the division could change into 1:2. Possible measures for increasing the dayly routine percentage of 13% are discussed.