PURPOSE: Tropisetron (Nabovan (R)) is a new specific 5-HT3 receptor antagonist with a long terminal half life in plasma and high bioavailability after oral intake. We compared the antiemetic effectiveness and tolerability of tropisetron with ondansetron in the highly emetogenic chemotherapy (including cisplatin > or =50 mg/m2). MATERIALS AND METHODS: Thirty-nine patients were administered in a randomized, multicenter, open, cross-over study and received either tropisetron plus dexamethasone (n=31) or ondansetron plus dexamethasone (n=34) during six days of two successive cycles of chemotherapy. RESULTS: Total control of vomiting with either Ondansetron or tropisetron was 94.2 % vs 93.5 % in D1 (P=0.157); 90.6 % vs 93.1 % in D2 (P=0.18); 90.3 % vs 93.1 % in D3 (P=0.655); 96.4% vs 96.4 % in D4 (P=0.157); 96.4 % vs 100 % in D5 (P=0.317); 96.4 % vs 100% in D6, respectively. The duration of nausea showed significant decreasements in tropisetron at D5 and D6 (P=0.025, P=0.03, respectively), but the severity of nausea and performance status showed no significance. Headache and constipation were the most common side effects in both groups. CONCLUSION: There was no significant difference in efficacy and tolerability between tropisetron and ondansetron in the cisplatin-based chemotherapy.