Background: Dexmedetomidine has emerged as a wonder drug in regional anesthesia practice owing to its co-analgesic properties. However, there is a lack of literature for comparison of intrathecal with intravenous routes of dexmedetomidine administration on the effectiveness of subarachnoid block. Methods: Prospective, randomized, double-blind study was carried out in 40 patients aged 18-60 years with ASA I and ASA II physical status scheduled for elective infraumbilical surgery under subarachnoid block. Participants were randomly divided into two groups. Subarachnoid block was administered with 3ml of hyperbaric Bupivacaine in both groups. Patients in Group 1 received intrathecal 5µg dexmedetomidine and intravenous infusion of normal saline during surgery. Patients in Group 2 received intravenous bolus dexmedetomidine infusion of 0.5 µg /kg followed by maintenance infusion of 0.5 µg/kg/hr. Block characteristics, Ramsay Sedation score and hemodynamic variables were recorded for all patients. Results: The duration of motor block, the dermatomal level achieved and duration of analgesia was higher in group 1 compared to group 2. The groups were similar with respect to onset time of sensory and motor block, sedation score and hemodynamic variables. There were no significant side effects in either of the groups. Conclusions: Dexmedetomidine by either intrathecal or intravenous route is an attractive adjuvant for infraumbilical surgical procedures performed under subarachnoid block. In cases where the requirement is to prolong duration of intraoperative anesthesia and postoperative analgesia intrathecal route is desirable. Whereas, in daycare surgeries where the requirement is only to intensify the block in the intraoperative period with early postoperative ambulation intravenous route is preferable.