The incidence of postoperative nausea and vomiting (PONV) in adult women is 2-4 times that in men. Gynecologic laparoscopic surgery increases incidence of PONV. Whether the phase of menstrual cycle is a risk factor for PONV after gynecologic laparoscopy is controversial (1, 2, 3). We investigated in prospective, double-blind, observational study if the phase of menstrual cycle has influence on the incidence of PONV in patients undergone general anesthesia for gynecologic laparoscopic surgery. After obtaining IRB approval and informed consents, 72 women in child bearing age, ASA PS I and II, scheduled for laparoscopic gynecological surgery were assigned into three groups according to phase of the menstrual cycle at the time of anesthesia: G1 - follicular phase (days 1-8), G2 - ovulatory phase (days 9-15) and G3 - luteal phase (days 16 to the end). The day of menstrual cycle was calculated from the first day of the last cycle. The exclusion criteria were: obesity, diabetes, gastrointestinal paresis, pregnancy, breast-feeding, irregular cycles, use of antiemetics, hormones, steroids and psychotropic drugs before surgery. Patients received 7.5 mg of midazolam PO 1 h before the surgery. No PONV prophylaxis was given. Anesthesia was induced with thiopental 5mg/kg, vecuronium 0.1 mg/kg and fentanyl 1-2 μ g/kg, followed by 10 mL/kg saline and maintained with sevoflurane ∼ 1MAC and air in 40% oxygen. Patients were considered to have had PONV if at least one episode of nausea, vomiting or retching or any combination of these occurred during 24 hours postop. Diclofenac IM and pethidine IV was used for postoperative pain and metoclopramide IV for PONV. Data were analyzed using Χ ² ; , Kruskal Wallis and Mann-Whitney test and expressed as mean (SD). P