AbstractRimcazole (BW234U), a substituted carbazole compound, has been reported to be effective in treating acutely ill schizophrenic patients without significant extrapyramidal side effects. A two‐phase study was done to assess the efficacy and safety of rimcazole in the maintenance treatment of schizophrenia. Study I was a double‐blind comparison of rimcazole (50–300 mg daily) with haloperidol (5–30 mg daily) with ten stable schizophrenic outpatients. Three of six patients relapsed on rimcazole, while there were no relapses on haloperidol. One patient dropped out of each group. Extrapyramidal side effects were minimal in the rimcazole group, and two patients with tardive dyskinesia showed marked improvement in AIMS Scores. Study II was an open label trial of rimcazole using a higher maximum dose of 450 mg daily in seven schizophrenic outpatients. Four of the seven patients relapsed, at a mean of 7 weeks, one dropped out, and two patients remained stable. While the drug was generally well tolerated, both of the nonrelapsing patients developed transient elevations in liver transaminases. The small sample size in these studies prevents definitive conclusions to be drawn. There may be subgroups of schizophrenic patients who can be successfully maintained on rimcazole with less morbidity than from standard neurolepti