Objective: Postoperative nausea and vomiting (PONV) is a common problem and its cause is multifactorial. The relationship between PONV and nitrous oxide is under debate. The aim of this study was to evaluate the relationship between nitrous oxide and PONV in patients undergoing laparoscopic cholecystectomy. Patients and Methods: Forty premedicated female patients, ASA I or II, age 18-60 years and weigthing between 50-80 kg, were scheduled to undergo elective laparoscopic cholecystectomy. They were randomly assigned to two groups. Anaesthesia was induced in all patients with thiopental sodium, remifentanil and atracurium. Anaesthesia was maintained with sevoflurane, nitrous oxide in oxygen in group I and sevoflurane, air in oxygen in group II. Perioperatively remifentanil was infused in all patients. The patient's PONV and pain scores were assessed 24 hours postoperatively. Results: In group I, PONV scores were significantly higher at the 1st and 4 th h postoperatively, however, there was no significant difference in group II. There was no significant difference in PONV and pain scores and the percentage of patients needing antiemetics between groups. No correlation was found between PONV and postoperative pain. Conclusion: Our data demonstrate that nitrous oxide does not increase the incidence or severity of PONV in patients undergoing laparoscopic cholecystectomy.