The anti-emetic effect of corticosteroid during cancer chemotherapy with cis-diamminedichloroplatinum (II) (CDDP) is analyzed retrospectively. From November 1981 to April 1984, 23 of 50 patients receiving CDDP were given corticosteroid as an anti-emetic. Corticosteroids, methylprednisolone (80-500 mg/day) or hydrocortisone (200-480 mg/day), were administered intravenously for 1 to 3 doses. Including 4 patients who had no symptoms, 60% of patients were free from nausea and vomiting. The incidence of gastrointestinal symptoms was significantly lower than that in patients who were not given corticosteroid. Corticosteroid reduced gastrointestinal symptoms in 2 of 3 patients who had prior CDDP treatment. There were no remarkable adverse reactions except acne in 2 patients. A further controlled study is needed to determine the appropriate dose and modality of administration of corticosteroid.