Ninety recently-admitted acute schizophrenic patients, aged 18 to 40 years (mean age: 29) were stratified by schizophrenic subgroups, distributed at random among three groups (pipotiazine, haloperidol and placebo), and evaluated for 27 days by the Brief Psychiatric Rating Scale (BPRS) and Clinical Global Impression (CGI). All groups received 20 mg of haloperidol and 50 mg of chlorpromazine im during the first 3 days, followed by wash-out for 2 days and then oral pipotiazine, haloperidol or placebo for the following 21 days. The dosage was adjusted to the clinical response of the patients and the mean dose was 21.4 mg for pipotiazine and 11.5 mg for haloperidol. At the end of the trial on the 27th day there was no significant difference between pipotiazine and haloperidol, but the effect of both active drugs was significantly different from that of the placebo. In the period corresponding to the 6th to 27th day, extrapyramidal side effects (EPS) occurred to the same extent in the pipotiazine and haloperidol groups, with predominance of Parkinsonian reactions, and no EPS were observed in the placebo group. Our data for a Brazilian population confirm the only other double-blind study of these drugs reported in the literature.