The most frequently used ventilation mode in general anaesthesia is VCV, which utilises a constant flow to deliver a target tidal volume and ensures minute ventilation, it may result in high airway pressures in laparoscopic surgery. PCV which has been initially proposed in ICU patients with acute respiratory distress syndrome (ARDS) as an alternative to VCV, is less frequently employed in general anaesthesia. Data was collected from all the consenting patients who will be scheduled for elective laparoscopic cholecystectomy surgery under general anaesthesia with endotracheal intubation in Department of Anaesthesiology. The mean (SD) of exhaled tidal volume in the VCV group are 424.7 (53.9), 418.9 (49.3) and 416.7 (48.5) at T1, T2 and T3 respectively. In the PCV group are 355.8 (36.4), 368.6 (33.0) and 357.8 (34.2) at T1, T2 and T3 respectively. Statistically there is a significant difference between group VCV and PCV at T1 (p=0.001), T2 (p=0.001) and T3 (p=0.001).