Background: Laparoscopy cholecystectomy for the surgical treatment of cholelithiasis has been considered the gold standard. The referred pain to the shoulder (omalgia) may be present to 63% of the patients and limits outpatient management. Objective: The study was to evaluate the usefulness of acetazolamide associated with ketorolac for reduction of the omalgia to minimally invasive treatment. Methods: We performed a clinical trial, randomized, double blind in patients undergoing laparoscopic cholecystectomy to assess the reduction of post-operative omalgia comparing ketorolac and ketorolaco+acetazolamida. 31 patients in each group were studied. The study group: 250 mg of acetazolamide before anesthetic induction and 30 mg of ketorolac in the immediate postoperative period. Control group: one tablet of placebo prior to the anesthetic induction and 30 mg of ketorolac in the immediate postoperative. The presence of omalgia was assessed using the analog visual scale. The variables recorded included: age, sex, flow of carbon dioxide intra-abdominal pressure, surgical time, urgent or elective surgery, omalgia, severity of pain evaluated by analog visual scale, addition analgesia. Results: Both groups were homogeneous and statistical analysis showed no differences in the variables studied. The omalgia in the study group was presented at 9.67% and in the group control was the 58.06% (p < 0.001). Conclusion: 250 mg oral acetazolamide associated 30 mg of ketorolac reduces significantly the development of omalgia in patients undergoing laparoscopic cholecystectomy.