Background: Buprenorphine is a partial agonist-antagonist opioid, and is thirty times more potent than morphine, having both spinal and supra-spinal components of analgesia. It has high lipid solubility, high affinity for narcotic receptors, and prolong duration of action. Literature on the anesthetic potency of intrathecally administered bupivacaine with buprenorphine is less, which prompted us to conduct this study. Method: This was a prospective randomized case control study. 100 patients of ASA GRADE I AND II were equally divided in two groups. Control group (A) received 2.8 ml hyperbaric (0.5 %) bupivacaine(14mg) + 0.2 ml normal saline and study group (B) received hyperbaric (0.5 %) bupivacaine(14mg) + 0.2 ml buprenorphine (60mcg) in subarachnoid space in patients undergoing lower limb orthopaedic surgeries. Patients was evaluated for post-operative analgesia by Magills score, number of hypotensive episodes, bradycardia, respiratory depression intra-operatively and post operatively. Any side effects intra-operatively and postoperatively were monitored. Result: Hemodynamic stability was significant in study group(B). Duration of postoperative analgesia was significantly longer in the study group (B) with mean value of 14.69+/- 3.83 hours than in control group which was 4.92 +/-0.82 hours (p value <0.0001) without having any side effects. Conclusion: It can be concluded from our study that buprenorphine reduces dose of local anaaesthetic to achieve good quality of sensory block and postoperative analgesia