In a randomised double-blind study, 46 first episode schizophrenics were given pimozide or flupenthixol for up to 5 weeks; the mean daily dose at the end was 18.8 mg pimozide and 20 mg flupenthixol. There were no significant between-drug differences in the effect on mental state or behaviour; positive schizophrenic symptoms responded to treatment, negative symptoms did not. Most patients required anti-Parkinsonian medication. Poor response was associated with 'organicity'. A switch to maintenance therapy after 5 weeks, the outcome of successful treatment and patient cooperation, was achieved in only 54%. There was no relationship between plasma prolactin levels and severity of schizophrenic symptoms in unmedicated patients. Pimozide produced greater elevation of plasma prolactin. Plasma neuroleptic levels showed drug compliance was satisfactory throughout in only 54%.