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 two treatment methods using this drug and compared the antiemetic effect of this method with that of standard bolus intravenous injection on nausea and vomiting associated with anticancer drug including 75 mg/m cisplatin (CDDP). The two-treatment group received an intravenous bolus injection of 5 mg azasetron before and 8 hours after the start of chemotherapy, and a standard group was given an intravenous bolus injection of 10 mg azasetron only once a day. The inhibitory effect on vomiting in the two-treatment group was significantly greater than those of the standard group on day 1 and 2 (p = 0.0458, p = 0.0273), and the inhibitory effect on nausea of the two-treatment group tended to be superior those of the bolus group on day 2 (p = 0.0533). No adverse effects were observed in either group of this study. From these data, the two-treatment approach was considered to be highly effective in prophylaxis of nausea and vomiting induced by anticancer drug.