Clinical usefulness of ondansetron as an antiemetic for the treatment of nausea and vomiting induced by anticancer drugs including cisplatin (> or = 50 mg/m2) was evaluated by a multi-institutional, double-blind comparative study with placebo with inpatients with various malignancies. In this study, efficacy, safety and usefulness of single dose of ondansetron (4 mg) or placebo (physiological saline), given intravenously for initial nausea and vomiting were observed for 24 hours after treatment. Clinically, very effective or effective response was seen in 64% (16/25) of the group O (ondansetron) and 5.9% (1/17) of the group P (placebo). No clinically significant adverse effects or abnormal laboratory test values were reported in the group of O. Diarrhea (1 case) and the elevation of laboratory test values (GOT.GPT, T-bilirubin, LDH, in 3 cases) were reported in the group of P. General safety assessment was considered "safe" in 100% of both group O and group P, and there was no statistical difference between two groups. Usefulness was considered as "useful" in 64% (16/25) of group O and 6.3% (1/16) of group P, and O was significantly better than group P (p < 0.001) level. In conclusion, ondansetron provides a safe and effective antiemetic measure when employed therapeutically against nausea and vomiting induced by regimens including cisplatin.