Thirty-nine chronic schizophrenic patients were selected for a 12-month double-blind evaluation of the effectiveness of pipothiazine palmitate (PPT) and flupenthixol decanoate (FPX) in the maintenance management of their illness. Allocation was at random and, in order to allow constant injection intervals, the patients typically received every 2 weeks either 40 mg of flupenthixol decanoate or alternating injections of 100 mg of pipothiazine palmitate and placebo. At monthly intervals the patients were assessed using both a battery of rating scales (which included the Brief Psychiatric Rating Scale (BPRS), the Extrapyramidal Symptoms Rating Scale (EPS] and a general side-effects evaluation. At 3-monthly intervals they were also rated on the Comprehensive Psychiatric Rating Scale (CPRS) and the Zung Depression Scale. Haematological and biochemical tests were performed every 3 months. Both drugs provided good control of psychotic symptoms and side-effects were not troublesome. No substantial difference was detected on the CPRS and the Zung scales. There was a trend in favour of PPT on the BPRS survey, detectable at 6 months and reaching statistical significance by 12 months. We conclude that the PPT regime is at least as effective as the FPX treatment and probably more so. It is possible that even longer periods of control could be obtained with PPT.