Postoperative nausea and vomiting (PONV) are unpleasant experiences. However, there is no drug that is completely effective in preventing PONV. Whereas cost effectiveness analyses rely on specific health outcomes (e.g., years of life saved), cost-benefit analyses assess the cost and benefit of medical therapy in terms of dollars. We hypothesized that patients were willing to pay for a hypothetical new drug that would eliminate PONV. Eighty elective day surgical patients using general anesthesia participated in the study. After their recovery in the postanesthetic care unit, they were asked to complete an interactive computer questionnaire on demographics, the value of avoiding PONV, and their willingness to pay for an antiemetic. Patients were willing to pay US$56 (US$26--US$97; median, 25%--75%) for an antiemetic that would completely prevent PONV. Patients who developed nausea (n = 21; 26%) and vomiting (n = 9; 11%) were willing to pay US$73 (US$44--US$110) and $100 (US$61--US$200; median, 25%--75%), respectively (P < 0.05). Seventy-six percent of patients considered avoiding postoperative nausea and 78% of patients considered avoiding vomiting as important (> or = 50 mm on a 0--100-mm visual analog scale). Nausea or vomiting in the postanesthetic care unit, greater patient income, previous history of PONV, more importance placed on avoiding nausea and vomiting, increasing age, and being married are independent covariates that increase the willingness to pay estimates. Patients associated a value with the avoidance of PONV and were willing to pay between US$56 and US$100 for a completely effective antiemetic.