Atypical antipsychotics like olanzapine are more efficacious in treating negative symptoms and have less side effects. Nevertheless, important adverse effects of olanzapine are, for example, weight gain and hyperglycemia. Perazine in combination with carbamazepine has shown satisfying results in several single-schizophrenia patients, leading to the hypothesis of being equal or even superior to atypical antipsychotic monotherapy. The aim of the present study was to survey the hypothesis that perazine in combination with carbamazepine have an outcome and risk of side effects comparable to olanzapine. Eleven patients with DSM-IV schizophrenia received 14.0 +/- 5.0 mg/day olanzapine and 12 patients received 360.0 +/- 196.0 mg/day perazine in combination with 404.0 +/- 229.0 mg/day carbamazepine. Symptoms and neuropsychological state were assessed 3 times (days 0, 7, 21) using the Positive and Negative Syndrome Scale and the Brief Psychiatric Rating Scale. The neuropsychological state was assessed by the following neuropsychological tests: Benton, d2, ZVT, VLMT and MWT-B. Data were analyzed of variance for multiple dependent variables and repeated-measures multivariate analysis of variance. Positive and Negative Syndrome Scale and Brief Psychiatric Rating Scale scores showed superior improvement in the group receiving olanzapine. Olanzapine offers a more favorable response in positive symptoms than does perazine in combination with carbamazepine. The effect on negative symptoms is favorable in both forms of therapy and no significant differences between the groups could be determined. In both groups, treatment was associated with improved performance in cognitive tests; however, no differences were determined in the effects of the drugs. Results suggest that olanzapine offers a better response in positive symptoms than perazine in combination with carbamazepine.