In a 28‐day, dose‐range study, 11 chronic schizophrenic inpatients newly admitted to the hospital with acute exacerbations were administered a new antipsychotic, BW 234U, in daily doses ranging from 100 to 400 mg/day on a fixed/flexible schedule to determine therapeutic dose range, safety, and psychotropic activity with special regard to possible antiaggressive action. The results of weekly assessments with standard psychiatric rating instruments indicate that BW 234U has dual psychotropic action—an antipsychotic and an activating effect—that may have potential value in the treatment of depressive illness. The drug appears to be relatively free from neurologic, cardiovascular, anticholinergic, and CNS‐depressant side effects. Copyright © 1983 Alan R. Liss, Inc.