A pilot study suggesting the usefulness of intravenous diazepam as an antiemetic for adult patients receiving cis-diamminedichloroplatinum is presented. Observations included 24 patients and 34 courses of therapy. Patients received diazepam and prochlorperazine, and the incidence of vomiting and subjective evaluation of nausea were compared to previous courses of therapy with prochlorperazine alone. A positive response was observed in 87% of the patients. Use of other antiemetics is briefly reviewed.