Objective: Limited data are available on the use of the perfusion index (PI) and the pleth variability index (PVI) during laparoscopicbariatric surgery. We investigated the effects of pneumoperitoneum and the reverse Trendelenburg position on these indices.Materials and Methods: PI, PVI, heart rate (HR), blood pressure, SpO2 and ventilation parameters were recorded before anaesthesiainduction (T0), 5 min after endotracheal intubation (T1), immediately before surgery, after the patient had been in the reverseTrendelenburg position for 5 min (T2), after inflating the abdomen with CO2 in reverse Trendelenburg (T3), after the abdomen hadbeen deflated (T4) and 5 min after extubation (T5).Results: General anaesthesia induced an increase in the PI (P