OBJECTIVE Cyclophosphamide (CY)-containing chemotherapy is usually characterized as moderately emetogenic. The aim of this study was to evaluate the efficacy of different antiemetics in the control of acute emesis in repeated cycles of moderately emetogenic chemotherapy. METHODS A total of 101 patients with breast cancer (41, 40.6%), Hodgkin's disease (46, 45.5%) and non-Hodgkin's lymphoma (14, 13.9%) were studied. These patients received standard protocols of CY-based (>/=750 mg/m(2)) moderately emetogenic chemotherapy. Intravenous (i.v.) bolus metoclopramide (MCL), ondansetron (OND) and their combinations with corticosteroids (CS) were administered to the patients. The MCL-alone group of patients was used as control group. Emesis was evaluated during the first 3 courses of chemotherapy according to the internationally accepted criteria. All calculations were performed using the SPSS-5.0 statistical computing package. RESULTS During the first course of chemotherapy no differences in the efficacy between the control group and the other groups were noted (p >0.05). On the contrary, during the next 2 courses the efficacy of MCL progressively decreased and OND, OND plus CS and MCL plus CS showed significantly higher efficacy compared with MCL alone (p <0.05). Excluding MCL alone, the other antiemetics showed similar efficacy in the 2nd and 3rd course of chemotherapy (p >0.05). Patients aged over 35 years had more severe emesis. CONCLUSIONS The combination of MCL plus CS showed similar efficacy compared with OND and OND plus CS, and is cost-effective. The control of acute emesis in the first course and the patients' age are significant factors, influencing the efficacy of the antiemetic therapy in repeated courses of moderately emetogenic chemotherapy.