BACKGROUND: Most recently, the antiemetic effects of high inspired oxygen have been discussed and various results have been reported according to the types of surgeries and the groups of patients. In ophthalmic surgical patients, surgical procedures involving intraoperative manipulation of the eye and giving rise to residual eye discomfort were associated with the increased incidences of postoperative nausea and vomiting (PONV). The antiemetic effect of 80% inspired oxygen for the patients undergoing vitreoretinal surgery is unknown. Therefore, we examined the efficacy of 80% inspired oxygen in the decrease of the PONV incidences after vitreoretinal surgery under general anesthesia. METHODS: 170 adults under 70 years of age have received standardized sevoflurane anesthesia. After tracheal intubation, they were randomly assigned to two groups: 30% inspired oxygen in air (Group 30), and 80% inspired oxygen in air (Group 80). Postoperative nausea and vomiting were evaluated at the 2, 6, and 24 h postoperatively by an investigator unaware of patients' allocation. RESULTS: There was a significantly lower incidence of PONV during the first 2 h postoperatively in the Group 80 (22%) compared with the Group 30 (40%) (P = 0.024). The Group 80 (33.8%) showed the decreased incidence of PONV during the first 24 h postoperatively compared with the Group 30 (48.8%), but these differences were not statistically significant (P = 0.081). CONCLUSIONS: The use of 80% inspired oxygen during vitreoretinal surgery reduced the incidence of PONV during the first 2 h postoperatively.