The potent serotonin receptor (5-HT3) antagonists are new highly selective agents for the prevention and control of chemotherapy-induced nausea and vomiting that have been shown to be comparable to or more effective than traditional metoclopramide regimens. This study was designed to compare the antiemetic efficacy of dolasetron and metoclopramide in chemotherapy-naive and non-naive cancer patients receiving high-dose cisplatin-containing chemotherapy. This multicentre, double-blind, randomized trial compared the efficacy and safety of single i.v. doses of dolasetron mesilate salt (1.2 or 1.8 mg/kg) and metoclopramide (7 mg/kg) in 226 patients for the prevention of acute emesis and nausea associated with the administration of high-dose (> or = 80 mg/m2) cisplatin. Efficacy and safety were evaluated for 24 h. Complete responses were achieved by 57%, 48%, and 35% of patients given dolasetron mesilate 1.8 mg/kg (P = 0.0009 vs metoclopramide), dolasetron mesilate 1.2 mg/kg (P = 0.0058 vs metoclopramide), and metoclopramide, respectively. Overall, dolasetron was significantly more effective than metoclopramide for time to first emetic episode, nausea, patient satisfaction, and investigator global assessment of efficacy. Males, chemotherapy-naive patients, and alcoholics had higher response rates. Dolasetron was well tolerated, with mild-to-moderate headache most commonly reported. Twelve percent of patients receiving metoclopramide reported extrapyramidal symptoms compared with 0% of patients receiving dolasetron. In conclusion, dolasetron mesilate was effective for the prevention of CINV with high-dose cisplatin. Single i.v. doses of dolasetron mesilate were more effective than 7 mg/kg metoclopramide in preventing nausea and vomiting induced by highly emetogenic cisplatin-containing chemotherapy. In addition, 1.8 mg/kg dolasetron mesilate consistently produced the highest response rates and appears to be the most effective dose for further clinical development.