OBJECTIVE: To evaluate the efficacy and safety of dexamethasone administered intravenously at three different doses (4 mg, 8 mg, 16 mg) for the prevention of nausea and vomiting after dilatation and curettage. METHODS: In a prospective, randomized, double-masked, placebo-controlled trial, 120 women received placebo or dexamethasone intravenously at doses of 4 mg, 8 mg, or 16 mg immediately before induction of anesthesia (n = 30 in each group). Propofol-based general anesthetic was used. Emetic episodes and safety assessments were performed. To estimate a sufficient sample size, it was calculated that 30 patients per group would be required with alpha = .05 and beta = .2. RESULTS: The rate of patients who were emesis-free (no nausea, retching, or vomiting) 0-24 hours after anesthesia was 57% with dexamethasone 4 mg (P = .796), 87% with dexamethasone 8 mg (P = .005), and 87% with dexamethasone 16 mg (P = .005), compared with placebo (50%). Patients who had received dexamethasone 8 mg or 16 mg were more satisfied than those who had received placebo (P < .05). No clinically important adverse events were observed in any of the groups. CONCLUSION: Dexamethasone 8 mg is an effective antiemetic for preventing postoperative nausea and vomiting 0-24 hours after anesthesia in women undergoing propofol-based general anesthesia for termination of pregnancy. Increasing the dose to 16 mg provided no additional benefit. (C) 2002 by the American College of Obstetricians and Gynecologists.