Background: Clonidine, an 2-agonist, has been used intrathecally as an adjuvant to bupivacaine in spinal anaesthesia, for prolonging anaesthesia and postoperative analgesia. This study was designed to compare efficacy of two doses of intrathecal clonidine (15µg versus 30µg) for prolongation of anaesthesia, with maintainance of heamodynamic parameters, to find out lowest possible effective dose. Methods: Sixty patients, scheduled to undergo lower abdominal surgery, were enrolled. They were randomly divided into two groups, of 30patients in each group. Group BC15 received 15mg (3ml) of hyperbaric bupivacaine plus 15µg clonidine plus 0.1ml of normal saline and Group BC30 received 15 mg hyperbaric bupivacaine plus 30 µg (0.2ml) clonidine, thus keeping volume of injectable solution constant to 3.2 ml, in both groups. Results: Highest level of sensory block achieved, was recorded which was almost similar in both groups. Time taken to achieve highest level of sensory block , time to achieve two segment regression, time to achieve regression to L1 dermatome , time to first analgesic request , time to achieve maximum Bromage scale 4, time to achieve regression back to minimum Bromage scale 1 and haemodynamic changes, showed no stastically significant difference amongst both groups (P value >0.05). Conclusion: Both doses of intrathecal clonidine i.e.15µg and 30µg with bupivacaine, produce equal prolongation of sensory and motor block alongwith time to first analgesic request.So, clonidine15µg intrathecally with bupivacaine is preferred over 30µg or higher dose to achieve prolongation of desired sensory and motor block alongwith postoperative analgesia with clinically insignificant haemodynamic effects.