OBJECTIVE To compare the effects of premedication with intravenous paracetamol versus ketorolac, in decreasing intraoperative anaesthetic and postoperative opioid analgesics requirements in patients undergoing laparoscopic cholecystectomy. METHOD An experimental, prospective, comparative, double blind, and randomised clinical trial was conducted to determine intraoperative opioid requirements, and pain and analgesic requirements in the postoperative period in 100 healthy patients undergoing laparoscopic cholecystectomy. They were randomised into 2 groups: Group 1: pre-medicated with paracetamol 1g, and Group 2: with ketorolac 30mg (both administered intravenously 30minutes prior to surgery). RESULTS There were no statistically significant differences between groups as regards intraoperative remifentanil use (Group 1: 0.0739±0.016μg/kg/min, Group 2: 0.0741±0.018μg/kg/min). The number of patients in Group 2 that had values of VAS>4 points (22.4%) was lower than in Group 1 (28.6%), but with no statistically significant difference. Of the patients who needed postoperative opioid rescue, most required a single rescue and application of analgesics during hospitalisation, that prevailed between 3 and 12hours, without any significant differences between groups. No adverse effects were observed in the study sample. CONCLUSION Paracetamol 1g IV given preoperatively decreased anaesthetic requirements and the need for postoperative analgesics similar to the preoperative administration of ketorolac 30mg IV.