A study was conducted comparing the efficacy of fluspirilene and butyrylperazine in preventing relapses in 40 male chronic schizophrenics (age range 22-62 years). The patients were divided in two groups of 20 and assigned to treatment with either fluspirilene mean dose 3,25 mg. intra muscularly weekly or butvrylperazine mean dose 7,3 mg. orally per day, mostly in combination with orphenadrine. Patients were assessed by the psychiatrist prior to and after one, 3 and 8 weeks of treatment and the number of relapses was scored. Behavioral changes were recorded by the nursing personnel every two weeks. In the fluspirilene group, 4 patients were dropped from the trial. No relapses occured in the remaining 16 cases and several patients were rated to be more spontaneous, friendly and active. In the butvrylperazine group, 3 patients relapsed and the number of patients showing more spontaneity, increased friendliness or activity was markedly lower. It was concluded that, although the duration of the trial was too short to attain statistically significant results, fluspirilene appears to be a useful drug for the prevention of relapses in schizophrenic patients who tend to discontinue neuroleptic maintenance therapy.