S5 INTRODUCTION: Gender is frequently listed as a variable associated with an increased incidence of perioperative nausea and vomiting. This association is based largely upon studies that examined nausea and vomiting following a variety of surgical procedures. The type of surgery may independently influence the incidence of postoperative nausea and vomiting and there is some evidence to suggest that the types of surgery females undergo may have a greater predilection for producing nausea and vomiting [1]. In addition most studies examined nausea and vomiting only in the first 24 hrs while both may persist for a much longer period. We examined the effect of gender on the incidence and course of nausea and vomiting in the first five days following arthroscopic anterior cruciate ligament reconstruction. METHODS: With IRB approval data collected from an ongoing quality assurance project was reviewed. All patients since 6/92 who underwent arthroscopically assisted anterior cruciate ligament reconstruction at our facility were asked to participate in an ongoing quality assurance project. Patients underwent standardized surgical repairs by 1 of 3 surgeons. Each patient received a standardized general anesthetic from one of nine anesthesiologists. Each patient was induced with Propofol, maintained with isoforane in nitrous oxide. Muscle relaxation and intubation were left to the discretion of the individual anesthesiologist. All patients received scheduled doses of ibuprofen and acetaminophen during the first five postoperative days. In addition all patients were allowed to use oxycodone prn during this time. The use of opioids and incidence of nausea requiring anti-emetic treatment and emetic episodes in PACU were recorded by recovery nurses. Each patient was asked to record on a standard form the use of supplemental opioids and the occurrence of nausea or vomiting on each of the first 5 postoperative mornings. RESULTS: A total of 736 patients were operated on between 11/92 and 6/98 complete data was available for 447 patients, 200 females and 247 males. (Figure 1)Figure 1DISCUSSION: This study clearly demonstrates the increased incidence of nausea and vomiting experienced by females following a single type of major orthopedic surgery performed under general anesthesia in an outpatient setting. This confirms findings of previous studies while controlling completely for type of surgery. The course of nausea and vomiting in both genders was prolonged well beyond typical follow up periods in most studies of nausea and vomiting. Future studies of nausea and vomiting should carefully control for gender effects and study beyond the first 24 hours.