The comparative efficacy of molindone and haloperidol, given by injection for the first 2-3 days of hospitalization and then continued orally for up to 4 weeks, is reported from an ongoing double-blind study. Efficacy and side effects were assessed by the Brief Psychiatric Rating Scale, Clinical Global Impressions, Treatment Emergent Symptom Scale, and Target Symptom Ratings. Analyses based on the first 35 patients who entered the study indicate that both drugs were effective and well tolerated. There were slight advantages for molindone early during the injectable phase of treatment and for haloperidol late during the oral portion of the study, but these differences were not clinically significant. No significant differences in side effects were found between the two drugs.