Background and Aims: Subarachnoid block for the lower limbs is a safe and reliable technique. The present study aimed to compare intrathecal nalbuphine and buprenorphine as adjuvants to ropivacaine 0.75% heavy in lower limb orthopaedic surgeries. Methods: Sixty patients admitted to the hospital during the study period and met the inclusion criteria were recruited and randomized either to nalbuphine group (Group N, n=30) and buprenorphine group (Group B, n=30). Group N: 22.5 mg 0.75% hyperbaric Ropivacaine (3.0 ml) + 1 mg Nalbuphine (0.5 ml) and Group B: 22.5mg 0.75% hyperbaric Ropivacaine (3.0 ml) + 60μg Buprenorphine (0.5 ml). Sensory block onset, sensory block regression, motor block onset, motor block regression, rescue time and blood pressure were evaluated and compared. Chi-square test and independent t-test were used for statistical analysis. Results: Sensory block onset, sensory block regression, motor block onset, motor block regression and time to first rescue analgesic were significantly shorter (p<0.001) in Group N than in Group B. The fall of BP from baseline was significantly more in group B compared to group N( p< .01). Hypotension was seen in 2 patients in Group B only but which resolved with IV fluids.