Background: Spinal anaesthesia is a preferred mode of anaesthesia for lower limb orthopedic surgery but limited duration of action remains a concern. Different adjuvants have been used intrathecally to prolong the duration of SAB .A quest for searching newer and safer adjuvant to local anaesthetic agents is always there as these orthopaedic procedures are associated with moderate to severe pain postoperatively. Aim: We compare the efficacy of intrathecal dexmedetomidine, fentanyl and nalbuphine for block characteristics and post operative analgesia in orthopedic surgeries. Material & Methods: 130 American Society of Anaesthesiologist 1and II patients undergoing lower limb orthopedic surgery requiring SAB were allocated randomly to four groups of 30 each to receive intrathecal dexmedetomidine 0.5mcg Group 1, fentanyl 25mcg Group 2, nalbuphine 0.4mg Group 3 and normal saline Group 4, added to 0.5% Isobaric levobupivacaine 12.5mg to make total volume 3 ml in each group. We assesed block characteristics, postoperative pain scores, time to use of first analgesic, 24 hour analgesic consumption, and additional analgesic consumption. Results: Onset of Motor blockade was fastest (8.67mins) in dexmedetomidine group (9.13mins) in fentanyl group, (10.07mins) in nalbuphine group and (12.18mins) in control group. Significant prolongation of time for need of first rescue analgesic was seen with the use of dexmedetomidine (485.35mins).Total 24 hours tramadol consumption was 196.42mg in dexmedetomidine group, 200mg in fentanyl group, 253.84mg in nalbuphine group and 222.72mg in control group. Conclusion: Dexmedetomidine as an adjuvant to 0.5% levobupivacaine seems to be a better alternative to fentanyl and nalbuphine.