Effect of Tramadol Adiministratian Previous to Induction of General Anesthesia on Prevention of Postoperative Shivering Atashkhoyi S1, Niazi M1, Iranpour A2 1 Dept of Anesthesiology, Al-Zahra Hospital, Tabriz University of Medical Sciences, Tabriz, Iran 2 Resident in Anesthesiology, Tabriz University of Medical Sciences, Tabriz, Iran Corresponding Author's Address: Dept of Anesthesiology, Al-Zahra Hospital, Tabriz University of Medical Sciences, Tabriz, Iran E-mail: siminatashkhoyi@yahoo.com Received: 14 July, 2008 Accepted: 13 Dec, 2008 Background and Objective: Shivering is a common post anesthetic complication. The relative efficacy of pharmacologic interventions used for the treatment of postoperative shivering is not well understood. The aim of this study was to evaluate the effect of administration of a 1mg/kg single dose Tramadol to induction of anesthesia in order to prevent post-anesthetic shivering. Materials and Methods: In this randomized, double-blind and placebo-controlled clinical trial, 60 patients which were classified based on American Association of Anesthesiologists (ASA) to physical status I or II selected for elective abdominal gynecologic surgeries by general anesthesia (GA). Before induction of anesthesia, 30 patients (study group), recieved a single dose of 1 mg/kg intravenous Tramadol, and the other 30 patients (placebo group) recieved 0.9% saline. Results: 3 patients (10%) of the study group and 17 patients (56.66%) of the placebo group experienced post anesthesia shivering (P<0.0001). Incidence of pain in the immediate postoperative period was significantly higher in the placebo group (90% vs 23.33% of patients respectively P<0.0001). No significant difference was observed in the incidence of postoperative adverse effects between the two groups. Conclusion: This study supports administration of single dose of 1 mg/kg Tramadol, prior to induction of general anesthesia in prevention of postanesthetic shivering.