Introduction: Nitrous oxide (N2O) increases risk for postoperative nausea and vomiting (PONV).(1) This effect appears to be dose/depended.(2) To minimize risk of using N2O some anesthesiologists use N2O at the end of volatile anesthetic anesthesia. We investigated if adding N2O at the end of isoflurane anesthesia had influence on extubation and PONV. Materials and Methods After obtaining IRB approval and informed consents, 64 women, ASA PS I-III, scheduled for laparoscopic assisted vaginal hysterectomy were randomized into two groups according to carrier gas: G0 – air in 30% oxygen (n=32) and G1 – the same mixture until last 30 minutes of surgery when 70% nitrous oxide and 30% oxygen was used (n=32). No PONV prophylaxis was given. Anesthesia was induced with thiopental 5 mg/kg, vecuronium 0.1 mg/kg and fentanyl 1-2 μg/kg IV, followed by 10mL/kg saline and maintained with isoflurane ~ 1MAC. Early recovery (time to extubation, eye opening, following commands, orientation) was measured by a blinded anesthesiologist. PONV and pain scores were measured at 2 h and 24 hours postoperatively. Diclofenac and meperidine was used for pain and metoclopramide for PONV. Data were analyzed using Chi-Square and Mann-Whitney test. P