The use of cisplatin may be associated with severe nausea and vomiting. Two separate, randomized, double-blind trials, comparing the anti-emetic effect of chlorpromazine with placebo and chlorpromazine with droperidol, were conducted in patients receiving cisplatin for ovarian cancer. Chlorpromazine was statistically superior to placebo in the control of nausea and vomiting in those patients treated with chlorpromazine had significantly less nausea than with droperidol, but there were no other significant differences between chlorpromazine and droperidol. Toxicities of chlorpromazine and droperidol were similar. Chlorpromazine shows useful activity against cisplatin nausea and vomiting.