A prospective, randomized, double-blind, placebo-controlled study was undertaken to evaluate the efficacy of dexamethasone for reducing postoperative nausea and vomiting (PONV) and analgesic requirements after middle ear surgery. Adult Japanese patients were allocated randomly to 1 of 3 groups (n = 30 each) to receive either placebo or dexamethasone at 2 different doses (4 mg and 8 mg) immediately before induction of anesthesia. Postoperatively, emetic episodes and analgesic requirements were evaluated by a blinded investigator. The rate of patients experiencing PONV during the first 24 h after anesthesia was 30% with dexamethasone 4 mg (P = 0.005) and 23% with dexamethasone 8 mg (P = 0.001) compared with 67% with placebo. The need for indomethacin for postoperative intolerable pain control was less in patients who had received dexamethasone 8 mg than in those who had received placebo (P = 0.018). No difference in analgesic requirement was found between the dexamethasone 4 mg and placebo groups (P = 0.396). No clinically important adverse events attributable to the study drug were observed in any of the groups. In conclusion, dexamethasone 8 mg is effective in reducing the rate of PONV and analgesic requirements in adult Japanese patients undergoing middle ear surgery.