CONTEXT Spinal anesthesia is preferred choice of anesthesia in lower abdominal surgeries since long time. However problem with this is limited duration of action, so for long duration surgeries alternative are required. Dexmedetomidine is a highly selective alpha-2-adrenergic agonist has property to potentiate the action of local anesthetic used in spinal anesthesia. Fentanyl is an opioid and it has also the same property. AIMS To compare the efficacy, analgesic effects, and side-effects of dexmedetomidine and fentanyl as adjuvant to bupivacaine for lower abdominal surgery. SETTINGS AND DESIGN The type of this study was double-blind randomized trial. SUBJECTS AND METHODS A total of 80 patients were randomly allocated in two Group D and Group F. Group D were injected injection bupivacaine 0.5% heavy × 3.0 ml + 0.5 ml of preservative free normal saline containing 5 μg dexmedetomidine. Group F were received injection bupivacaine 0.5% heavy × 3.0 ml + 0.5 ml fentanyl equivalent to 25 μg. STATISTICAL ANALYSIS USED The statistical analysis was performed using SPSS (Statistical Package for Social Sciences) version 15.0 statistical analysis software. RESULTS The results show that highest sensitivity level of T6 and T8 was achieved by higher proportion of subjects from Group D when compared to Group F and sensitivity level T7 was achieved by higher proportion of subjects of Group F when compared to Group D. Duration of analgesic properties was significantly higher in Group D when compared to Group F. CONCLUSION The findings in the present study suggested that intrathecal adjuvant use of dexmedetomidine as compared to fentanyl provides a longer sensory and motor blockade and also prolongs the postoperative analgesic effect.