The majority of patients receiving cisplatin at a dose of 120 mg/m2 experience delayed nausea and vomiting occurring between 24 and 120 hours after chemotherapy administration. Ninety-one patients who were receiving cisplatin (120 mg/m2) as initial chemotherapy were entered into this double-blind trial. All patients received intravenous (IV) metoclopramide, dexamethasone, and lorazepam for the control of acute emesis during the period from 0 to 24 hours after cisplatin. Patients were then randomized to one of three treatment regimens: placebo; oral dexamethasone, 8 mg twice daily for two days, then 4 mg twice daily for two days; or the combination of oral metoclopramide, 0.5 mg/kg four times daily for four days, plus oral dexamethasone administered as above. Forty-eight percent of individuals who received the two-drug combination of metoclopramide plus dexamethasone experienced delayed vomiting as opposed to 65% who were administered dexamethasone alone and 89% who received placebo (P = .006). Scores assessing the severity of delayed nausea and vomiting were consistently worse in individuals receiving placebo. The incidences of sleepiness, restlessness, heartburn, hiccoughs, loose bowel movements, insomnia, and acute dystonic reactions did not differ significantly among the three regimens and were mild and self-limited. The two-drug combination of oral metoclopramide plus dexamethasone is well tolerated, safe, and more effective than dexamethasone alone or placebo in controlling delayed vomiting following cisplatin.