AIM: To compare the efficacy and safety between quetiapine and clozapine. METHODS: There were 85 patients with first on-set schizophrenia in this study,43 patients treated with quetiapine 425? 56 mg?d -1 and 42 patients treated with clozapine 350? 73 mg?d -1 . The study lasted for 8 wk. The Positive and Negative Symptom Scale (PANSS) and Treatment Emergent Symptom Scale (TESS) were used to evaluate therapeutic and side effects. RESULTS: The PANSS scores in both groups decreased significantly after treatment with those two drugs(P