Introduction: This study investigated the analgesic and anti-shivering effects of oral consumption of clonidine and pregabalin in laparoscopic cholecystectomy. Method: In this randomized clinical trial, 67candidates for elective laparoscopic cholecystectomy-aged between 18 to 85 years. Before the administration of anesthetic medications and intubation, 1,2,3 groups received clonidine (0.2 mg, oral), pregabalin (50 mg, oral) and vitamin C (100 mg, oral), respectively. Blood pressure levels, heart rate, levels of pain, amount of shivering, nausea and vomiting were recorded. The data were analyzed in SPSS 11, using T-test and ANOVA test. Results: There was no significant difference between the three groups in terms of their blood pressure levels and heart rate before anesthesia, during the surgery and in the recovery room. There was no significant difference between the three groups in terms of shivering, nausea and vomiting. Clonidine significantly decreased pain at time 30 min [in the recovery room] compared with the other two groups; however, no significant difference was observed at other times. There was also no significant difference between the 3 groups in terms of pain levels, when leaving the recovery room. There was a significant difference between the clonidine and pregabalin groups and the vitamin C group in terms of pain levels, 24 hours after the surgery. Oral administration of both drugs reduced the pain levels compared with the vitamin C group, 24 hours after the surgery. Conclusion: Clonidine and pregabalin both reduced the postoperative pain in patients undergoing laparoscopic cholecystectomy, without changing the hemodynamic state.