Shivering is a frequent complication following spinal anesthesia (SA). It is more common in transurethral resection of the prostate (TURP) that may be due to absorption of large amount of irrigating fluids. We aimed to investigate the role of intrathecal dexmedetomidine in attenuation and prevention of shivering in patients undergoing TURP under SA. In a randomized, controlled trial, eighty patients were scheduled for elective TURP under SA. Patients were randomly allocated into two groups: control group (group C): patients received 2.5ml of hyperbaric bupivacaine 0.5% plus 0.5ml of normal saline and dexmedetomidine group (group D); patients received 2.5ml of hyperbaric bupivacaine 0.5%, plus 10μg dexmedetomidine in 0.5ml of normal saline. Hemodynamic parameters, shivering score and any adverse effects were recorded. The incidence of shivering was significantly reduced in group D, 6/40 patients (15%) compared with 23/40 patients (57%) in group C (P<0.001). The frequency of bradycardia, hypotension, number of patients treated with meperidine and ephedrine were significantly higher in group D compared with group C (P=0.048, P=0.043, P=0.011, P=0.043) respectively. There was insignificant difference in the incidence of nausea, vomiting and TUR syndrome in patients in both groups (p<0.05). Our results suggest that the use of 10μg intrathecal dexmedetomidine in patients undergoing TURP has a noticeable control of shivering even in occurrence of tolerable side effects.