In 92 patients receiving 270 cytostatic courses which all included cis-platinum, the antiemetic efficacy of medium- or high-dose metoclopramide was investigated. Metoclopramide was given intravenously 4 times during a 6-hour period (1/2 h before and 1 1/2, 3 1/2 and 5 1/2 h after cytostatic treatment) in a total dose of 1, 2, 4, 6, or 8 mg/kg. Nausea, emetic episodes, and side effects were registered during 24 h. The 1 mg/kg dose was given in 20 courses for which the average of emetic episodes was 16. In the four higher dosed groups the averages were 8, 8, 5, and 6, respectively. The average number of emetic episodes was significantly higher (p less than 0.001) in the 1 mg/kg metoclopramide group than in the 250 higher dosed courses. The frequency of side effects seemed independent of the dose in the interval 2-8 mg/kg while diarrhoea and other side effects tended to be less frequent in the 1 mg/kg metoclopramide group. Since antiemetic effect of metoclopramide in the dose interval 2-8 mg/kg did not increase with the dose, it is recommended to treat cis-platinum-induced emesis with 2 mg/kg metoclopramide given intravenously as 4 doses during a 6-hour period.