In a randomized double-blind, cross-over trial of 34 patients receiving cisplatin-based chemotherapy (20-100 mg/m2), the antiemetic effect of high-dose metoclopramide (HDM) (10 mg/kg iv. loading dose + 7 hours continuous infusion) + lorazepam (L) (2.5 mg x 4 po) was compared with low-dose metoclopramide (LDM) (70 mg) + L (2.5 mg x 2 po) + dehydrobenzperidol (5 mg x 2 im). Among the 29 patients who completed the cross-over, HDM significantly reduced the number of vomiting episodes (p = 0.002) and the degree of nausea (p = 0.004). Seventeen patients preferred the HDM and 4 the LDM regimen (p = 0.01). Sedation was seen in all but 1 patient, and was graded as severe in 6 patients receiving the HDM and in 2 patients receiving the LDM regimen. No extrapyramidal adverse reactions were seen. We conclude that high-dose metoclopramide + lorazepam is a safe antiemetic regimen and significantly superior to low-dose metoclopramide + lorazepam + dehydrobenzperidol. Owing to the severe sedation which occurs in some patients, the dose of lorazepam should be individually adjusted.