BACKGORUND: A laryngeal mask airway (LMA) for use with positive pressure ventilation are now firmly established in anesthesia practice. Positive pressure ventilation may cause leaks around the LMA cuff, leading to gastric distension and/or inadequate ventilation. The ProSeal laryngeal mask airway (PLMA) is a new laryngeal mask device with a larger cuff and a drainage tube, and offers tighter sealing compared with the classic LMA. We compared a PLMA with an endotracheal tube (ETT) in respect of gastric distension and ventilation. METHODS: Fifty ASA i-ii adults scheduled for an elective laparoscopic cholecystectomy were randomly assigned to an ETT or PLMA. Anesthesia was maintained with isoflurane in nitrous oxide and oxygen, and vecuronium. Ventilatory parameters were measured before and after intraabdominal gas insufflation. The surgeon assessed the degree of change in gastric distension under a laparoscope. RESULTS: incidence and degree in gastric distension were similar in both groups. Ventilatory parameters such as oxygen saturation, end-tidal CO2 tension, peak inspiratory pressure and minute volume didn't differ between either group. CONCLUSiONS:Positive pressure ventilation with a correctly placed PLMA permits adequate pulmonary ventilation. Gastric distension occurs with equal frequency for a PLMA and ETT.