In prospective alternative crossover test, we confirmed significant superiority of a three-drug combination of clonazepam (C) lorazepam (L) and dexamethasone (D) to (L) and (D) to control vomiting induced by 50 mg/m CDDP containing chemotherapy for gynecological malignancies (p less than 0.001). Vomiting frequency in initial 24 hours was 2.28 +/- 2.21 and 6.00 +/- 3.80 times a day respectively. According to this result, clonazepam, dexamethasone, metoclopramide and diphenhydramine (B) were used as a second regimen to control the vomiting in 80 mg/m CDDP containing chemotherapy for ovarian cancer patients. Clonazepam (2 mg 2 times p.o. -4 and 0 hrs before CDDP drip), dexamethasone (8 mg 5 times iv from -3 hrs each 3 hrs), metoclopramide (2.5 mg/kg iv loading from -2 hrs with 0.4 mg/kg/hr continuous infusion for 9 hrs) and diphenhydramine (30 mg/body 2 times im -2.6 hrs) were chosen to control CDDP-induced nausea and vomiting. These four drugs (C+L+D+B) prominently inhibited the chemo-induced vomiting up to 0.44 +/- 1.50 times a day, and 87.5% of courses was completely satisfactory.