Introduction: Dexmedetomidine is being increasingly used to prolong the duration of subarachnoid block. Various doses of dexmedetomidine are in practice. Isobaric Ropivacaine for its reduced cardiotoxicity and early motor recovery has gained edge over bupivacaine for subarachnoid block. Aims and objectives: To assess the efficacy and safety of two different doses of dexmedetomidine i.e 10µg and 15µg as an adjuvant to 0.75% isobaric ropivacaine intrathecally for abdominal hysterectomy surgeries. Materials and Methods: This prospective randomized and double blind study was conducted in 60 female ASA I and II patients scheduled for hysterectomy surgeries were randomized into two groups A and B. Group A received 2.5ml of 0.75% isobaric ropivacaine and 10µg dexmedetomidine whereas group B received 2.5ml of 0.75%isobaric ropivacaine and 15 µg dexmedetomidine. Onset and duration of sensory and motor block, hemodynamic variables were recorded and compared between the two groups. Results: The mean onset time of sensory and motor block of group A was 5.52±0.28mins and 6.95±0.22mins respectively whereas in group B was 4.48±0.35 and 6.1±0.28 mins which was statistically significant (p<0.0001).Duration of sensory and motor blockade in group A was 423±12.85 and 382±9.25mins respectively whereas in group B was 587±10.83 and 530±15.78 mins which was statistically significant (p<0.0001). There was no significance in hemodynamic and side effects between two groups. Conclusion: Our study showed that 15µg of Dexmedetomidine provided rapid onset and prolonged duration of subarachnoid block with isobaric 0.75% ropivacaine without significant side effects.