Gasretention in the peritoneal cavity plays an important role in inducing postoperative pain after laparoscopy, which is inevitably retained in the peritoneal cavity.The aim of this study was to detect the relation between the volume of residual gas and severity of shoulder and abdominal pain.In this Prospective study 55 women who were referred for laparoscopic cholecystectomy, were evaluated for the effect of residual pneumoperitoneum on postlaparoscopic cholecystectomy pain intensity. The pneumoperitoneum was graded as absent, mild (1-5 mm), moderate (6-10 mm) and severe (> 11 mm). Patients were followed for postoperative abdominal and shoulder pain using visual analogue scale (VAS), postoperative analgesic requirements, presence of nausea and vomiting, time of unassisted ambulation, time of oral intake and time of return of bowel function in the recovery room and at 6, 12 and 24 hours after operation.At the end of the study, 17 patients (30.9%) had no residual pneumoperitoneum after 24 hours; which 23 (41.81%) had mild residual pneumoperitoneum, eight (14.54%) had moderate pneumoperitoneum and seven (12.72%) had severe pneumoperitoneum. Patients with no or mild residual pneumoperitoneum had significantly lower abdominal and shoulder pain scores than whom with moderate to severe pneumoperitoneum (P = 0.00) and need less meperidine requirements (P = 0.00). Patients did not have any significant difference in time of oral intake, return of bowel function, nausea and vomiting percentages.We conclude that volume of residual pneumoperitoneum is a contributing factor in the etiology of postoperative pain after laparoscopic cholecystectomy.