Objective To explore the prophylactic effect of methylprednisolone combined with granisetron on postoperative nausea and vomiting.Methods Two hundred patients scheduled for lumpectomy of breast were randomly divided into four groups with 50 cases each.The patients in group M1 received a pre-anesthesia intravenous doses of methylprednisolone 25 mg,the patients in group M2 were injected methylpredsisolone 25 mg repeatedly four hours later,in group D received a pre-anesthesia doses of dexamethasone 5 mg,in group N normal saline 2 ml.All the four groups of patients received granisetron 3 mg intravenously at the end of surgery.The incidence of nausea and vomiting in the 24 hours were observed.Results The PONV incidences of group M1,M2,D,N were 36%,18%,38% and 58%.Both group M1,M2 and D significantly decreased the total inci-dence of PONV (P <0.05)in the 24 h.The incidence of PONV was significantly lower in group M2, compared with group M1 and group D respectively (P <0.05).Conclusion Methylprednisolone-gran-isetron combination is as equally effective as dexamethasone-granisetron combination for preventing PONV in lumpectomy,but repeated methylprednisolone after 4 h is more effective than dexametha-sone and single-used methylprednisolone.