Sixty-nine patients with malignant tumors receiving cancer chemotherapy, 90% including cis-platinum, were evaluated in a randomized crossover study for the antiemetic efficacy and the side effects of two antiemetic regimens: chlorpromazine (CPM) 2.5 mg/kg in 5 doses plus dexamethasone (DXM) 0.2 mg/kg in 2 doses, and high-dose metoclopramide (HD-MCP) 10 mg/kg in 5 doses plus the same dose of DXM. In 69% of 173 courses of chemotherapy, antiemetic response was achieved, and in 26% emesis was completely prevented. There was no statistical difference in the response to the antiemetic regimens, but 65% of the patients who completed 3 courses of chemotherapy preferred HD-MCP plus DXM. The main side effects of the treatment were drowsiness, nervousness, diarrhea and extrapyramidal reactions. HD-MCP plus DXM is recommended as a first line antiemetic treatment in patients receiving cancer chemotherapy. Patients resistant to this treatment should receive CPM plus DXM treatment.