Azasetron, a selective 5-HT3 receptor antagonist, has been previously shown to be highly effective in the prophylaxis of nausea and vomiting induced by anticancer drugs and is widely used in the clinical setting in Japan. In order to improve the antiemetic effect of azasetron, we designed a continuous intravenous infusion method of this drug and compared the antiemetic effect of this method with that of standard bolus intravenous injection on nausea and vomiting associated with anticancer drugs including 75 mg/m2 cisplatin (CDDP). A continuous group is intravenous bolus injection of 2.5 mg azasetron followed by 7.5 mg continuous intravenous infusion for 24 hrs, and a bolus group is intravenous bolus injection of 10 mg azasetron. The inhibitory effect on nausea of the continuous group was significantly superior to those of the bolus group on day 3 and 4 (p < 0.05) and inhibitory effect on vomiting of the continuous group was significantly superior to those of bolus group on day 2 (p < 0.05). No adverse effects were observed in either group of this study. From these data, continuous intravenous infusion of azasetron was considered to be highly effective in prophylaxis of nausea and vomiting induced by anticancer drugs.