The present study examined the efficacy of day care (DC) treatment against readmission to a mental hospital. Subjects were 65 out-patients with chronic schizophrenia after discharge. Day care treatment was defined as positive if patients were under DC treatment constantly for 4 months or more with a frequency of at least one visit per week. Information regarding demographic and disease-related factors was obtained from medical records at the time of discharge. Logistic regression analysis was used to calculate odds ratios (OR) and 95% confidence intervals (CI) with adjustment for confounding variables. The modestly preventive efficacy of DC treatment against readmission was observed within 2 years after discharge (adjusted OR 0.52; 95% CI 0.12-2.35). The present findings suggest that DC treatment may be preventive against readmission for schizophrenic out-patients.