AbstractIntroduction: Region anaesthesia is widely used and a safe anaesthetic technique. Shivering is frequently a known complication during regional anaesthesia. Shivering is a potentially serious complication. There are various methods available to control shivering during regional anaesthesia, which include non pharmacological methods and pharmacological methods using drugs. Drugs like tramadol, clonidine, are simple, cost-effective are useful for control of shivering. Methodology: The study was conducted in Gandhi Hospital, Secunderabad. All patients who developed post–spinal anaesthesia (intraoperative) shivering were randomly allocated to two groups: Group C (n=40) received clonidine 0.5 g/kg (intravenously) IV, and group T (n=40) received tramadol 0.5 mg/kg IV. Standard monitoring of pulse rate was done, and non-invasive blood pressure (NIBP), oxygen saturation (SpO2), body temperature (axillary) were recorded before the commencement of surgery and thereafter at every 5 minutes from the baseline i.e. subarachnoid block (SAB), for 30 min; and every 15 minutes, for the rest of the observation period. Observation and Results: In the present study, we found that clonidine is as effective as tramadol in treating post–spinal anaesthesia shivering, but the time interval from the commencement of treatment to cessation of shivering is quite less with clonidine (2.54±0.76 minutes) than with tramadol (5.03±1.02 minutes) (P=.0000001). The response rate was also higher in the clonidine group than in tramadol group, but the difference was not statistically significant (P=.03). Conclusion: In conclusion, both clonidine (0.5 g/kg) and tramadol (0.5 mg/kg) effectively treated patients with post–spinal anaesthesia shivering, but tramadol took longer time to achieve complete cessation of shivering than clonidine, the difference being statistically significant. So we conclude that clonidine offers better thermodynamics than tramadol, with fewer side effects. The more frequent incidence of side effects of tramadol, like nausea, vomiting and dizziness, may limit its use as an anti-shivering drug.