BACKGROUND: Although a laparoscopic cholecystectomy results in less pain than an open cholecystectomy, it is not a pain-free procedure. A controversy exists over the effectiveness and clinical value of intraperitoneal local anesthetics for treating pain after a laparoscopic cholecystectomy. We investigated the effects of intraperitoneal lidocaine on pain after a laparoscopic cholecystectomy. METHODS: Forty patients were randomly assigned to receive 200 ml saline containing 200 mg lidocaine or the same volume of saline instilled under the right hemidiaphragm and cholecystectomy site at the end of surgery. Intensity of abdominal and shoulder pain were assessed 0, 1, 6, 12, 24 and 48 hours after surgery and recorded on a visual analog scale (VAS) and verbal rating scale (VRS). RESULTS: The abdominal pain scores (VAS and VRS) were significantly lower in the lidocaine group than the control group at 0 - 24 hours after surgery (P < 0.05). The shoulder pain scores and incidence were significantly lower in the lidocaine group than the control group at 6 - 12 hours after surgery. In the lidocaine group, the incidence of epigastric and right flank pain were significantly lower than the control group. CONCLUSIONS: Intraperitoneal instillation of lidocaine significantly reduces shoulder and abdominal pain for 24 hours after a laparoscopic cholecystectomy.