Zotepine, a neuroleptic agent with additional 5-HT2 blocking properties, was compared with haloperidol in the treatment of schizophrenic patients with predominantly negative symptoms using a double-blind design. During the investigation period zotepine treated patients showed significant improvements in all rating instruments whereas haloperidol treated patients did not. Patients in the zotepine group developed fewer clinical side effects. The results of the presented study confirm the positive impressions gained in earlier open trials with zotepine.