Abstract: Objective : To compare the efficacy and safety of Tropisetron and Serotone in prevention of nausea and vomiting induced by total-body irradiation (TBI) and high-dose chemotherapy. Methods : All the eligible patients were randomized into group A or B. Group A: Tropisetron 5 mg was administered intravenously 15 minutes before high-dose chemotherapy and irradiation. Group B: Serotone 10 mg was administered intravenously 15 minutes before chemotherapy or irradiation. Results : 40 patients were evaluable for response, 19 in group A, 21 in group B. For acute nausea, the response rate was 89.5% in group A and 90.5% in the group B (P>0.05) respectively. For acute vomiting, the complete response rate was 78.9% and 85.7% (P30.05) respectively. The overall response rate for acute vomiting was 89.5% and 90.5% (P30.05) respectively. The overall and complete response rate of delayed vomiting were similar between two groups(P>0.05). Adverse effects were mild and well tolerated. Conclusions : Tropisetron and Serotone can effectively prevent the acute nausea and vomiting induced by total-body irradiation (TBI) and high-dose chemotherapy. However, the efficay of Tropisetron or Serotone alone in prevention against delayed nausea and vomiting appears unsatisfactory.