Background:Postoperative pain is considered as a reason of patient’s delay in discharge and disability aggravation. Therefore, multimodal approaches have been suggested in order to mitigate pain and decrease postoperative side effects.Objectives:The aim of this study was to evaluate analgesic effect of a single dose injection of dexamethasone on reducing postoperative pain in laparoscopic cholecystectomy.Patients and Methods:In this double-blind, prospective study, 122 patients aged 18-60 years old, whom were selected for laparoscopic cholecystectomy, were classified into two case and control groups, and 61 patients were included in each group. The case (D) group underwent general anesthesia and a single- dose intravenous injection of dexamethasone. The Control (C) group received general anesthesia and intravenous injection of normal saline. Total dose of consumed meperidine and pain intensity during first 24 hours were evaluated in both groups.Results:No significant difference existed between two groups regarding age, sex, weight and operation time. Pain intensity in group D was significantly less than group C (P < 0.01) after two, six and 12 hoursof surgery. No significant difference existed in pain intensity between two groups at the beginning of and 24 hours after the surgery (P > 0.05). Meperidine consumption in group D was significantly less than group C (P < 0.05).Conclusions:Findings of present study showed that single dose of intravenous dexamethasone, led to less pain intensity and amounts of meperidine consumption, in comparison with placebo.