Unilateral spinal anaesthesia can be used for inguinal hernia surgery. The advantage is that it provides a stronger block on the side of surgery and accelerated recovery of the nerve block, with better maintenance of cardiovascular stability. Hence it can be a valuable technique for high-risk patients. The aim: This randomized controlled trial was designed to evaluate the onset and duration of Sensory and motor block in both unilateral and bilateral spinal anaesthesia and the adverse effects of buprenorphine given intrathecally with 0.5 % bupivacaine for Spinal anaesthesia in patients scheduled for unilateral inguinal hernia surgery. Materials and methods: it is a сomparative two group randomized clinical study with 60 patients with 30 patients in Group U (UNILATERAL) and 30 patients in Group B (BILATERAL) is undertaken to study the changes in haemodynamics and side effects. Whereas, within the group (for the unilateral group) comparison of the time taken to reach L1, T12, T10 and the Bromage time between the surgical side and non-surgical side sides of surgery was done. Results: T10 -T12 spinal anaesthesia was achieved in both groups; the average time to anaesthetic onset in the unilateral group was 5.27±1.2 min, and in the bilateral, it was 5.90±1.02 min (p-value=0.32). Sensory and motor block lasted longer in the bilateral group when compared to the unilateral group; the incidence of side effects was limited to the occurrence of hypotension and bradycardia in the unilateral group than in the bilateral group. The success rate of unilateral spinal anaesthesia in our study was 100 %. Conclusion: Because of haemodynamic stability and faster recovery characteristics of unilateral spinal block, it can be used as a suitable technique in patients with a limited cardiovascular reserve and for outpatient anaesthesia.