The antiemetic efficacy of cinnarizine was assessed in 17 cancer patients receiving platin-based chemotherapy (cisplatin dose-range 30-160 mg, or carboplatin 270-600 mg) in a randomised, cross-over study. The patients were prophylactically given oral metoclopramide 3 x 1 mg/kg and lorazepam 2 x 1 mg with or without cinnarizine 3 x 75 mg. The antiemetic combination with cinnarizine prevented emesis completely on 51% of 35 days with chemotherapy and less than 3 emetic episodes occurred on 86% of the days, compared with 43% and 57% (p less than 0.01) without cinnarizine respectively. Severe nausea was significantly less frequent with cinnarizine and 59% of the chemotherapy days were without nausea, compared to 46% of the days without cinnarizine (p less than 0.05). Side-effects were uncommon and minor with both antiemetic regimens. The study suggests that addition of cinnarizine to metoclopramide and lorazepam improves antiemetic prophylaxis in low to medium dose platin-based chemotherapy.