The antiemetic efficacy of metoclopramide and lorazepam (MTC + L) versus alizapride and lorazepam (ALZ + L) was compared in 100 patients receiving chemotherapy, in a prospective randomized double-blind study. In highly emetogenic (HE) regimen (including platinum) patients received MTC 1 mg/kg or ALZ 3 mg/kg x 4 doses, and lorazepam 2.5 mg 30 min before therapy. In moderately emetogenic (ME) regimen patients received MTC 0.5 mg/kg or ALZ 1.5 mg kg x 3 doses, and lorazepam 2.5 mg 30 min before therapy. In both HE and ME regimen groups there was no statistically significant difference between MTC + L and ALZ + L treatments as regards the number of vomiting episodes, the duration of emesis and nausea, the intensity of nausea and side effects, but a statistically significant difference between treatments was found in the HE group where MTC-L was superior to ALZ + L in obtaining complete protection from vomiting (37 vs 11%, p = 0.05). No significant difference in side effects was observed.