PURPOSE: A study was designed to assess the effect of intraperitoneal instillation of ropivacaine in larparoscopic cholecystectomy patients using computerized patient controlled anesthesia (PCA). METHODS: From January 2009 to June 2009, 40 patients with uncomplicated, symptomatic cholecystitis with cholelithiasis who were referred to Chung-Ang University Medical Center for laparoscopic cholecystectomy were included in the study. Patients in group C (control group) received normal saline 100 ml and those in group I (instillation group) received intraperitoneal instillation of 2 mg/kg of ropivacaine diluted in 100 ml saline at the initiation of pneumoperitoneum. Patients were assessed for pain by blinded investigators at 6 time intervals after surgery; 2 hr, 4 hr, 8 hr, 12 hr, 24 hr, and 48 hr. The frequency at which patients pushed the button of the PCA on bolus requirement (FPB) was assessed by a patient-controlled module on the PCA machine. RESULTS: The mean total fentanyl consumption was lower in group I (367.39+/-85.88) than in group C (535+/-100.29) during the 48 hours (P<0.001). Fentanyl velocity and FPB showed significant difference between the groups (P<0.005). Visual analogue scale (VAS) measured pain scores were significantly lower in group I than in group C at 4 hr (P=0.027), 8 hr (P=0.010), 12 hr (P=0.011). CONCLUSION: Intraperitoneal instillation of ropivacaine at the beginning of laparoscopic cholecystectomy (LC) combined with normal saline infusion is an effective method for reducing pain after LC.