Aims: To study and compare the efficacy of intrathecal dexmedetomidine 5 μg versus intrathecal clonidine 50 μg as an adjuvant to 0.5% bupivacaine heavy 12.5 mg for spinal anesthesia. Materials and Methods: The present study is prospective, controlled double blind comparative clinical study on spinal block characteristics in patients scheduled for elective lower abdominal surgeries was undertaken to evaluate the efficacy and the safety of dexmedetomidine or clonidine as adjuvant to intrathecal hyperbaric 0.5% bupivacaine. Ninety patients were randomly divided into three groups, each group consisting of thirty patients (n = 30). Results: Dexmedetomidine group and clonidine group there is an early onset of both sensory and motor blockade and a higher level of sensory blockade compared to control group and duration of sensory, motor blockade and duration of analgesia are significantly prolonged in the dexmedetomidine group and clonidine group compared to the control group. There was a small percentage of patients who developed significant fall n blood pressure and heart rate which were easily managed without any deleterious effect. Seven patients each in dexmedetomidine group and clonidine group and two patients in control group developed hypotension requiring treatment. Five patients in dexmedetomidine group, four patients in clonidine group and one patient in control group developed bradycardia requiring treatment. More number of patients in the dexmedetomidine group and clonidine group were sedated and easily arousable. Conclusion: Dexmedetomidine is a better neuraxial adjuvant compared to clonidine for providing early onset of sensory and motor blockade, adequate sedation and prolonged postoperative analgesia.