Background and Objective Spinal anaesthesia is a well known technique used in lower abdominalsurgeries. Dexmedetomidine is a highly selective and potent alpha 2 agonist. Thepresent study was aimed to assess the effects of intravenous dexmedetomidinepremedication on spinal anaesthesia and analgesia with 0.5% HyperbaricBupivacaine. Methods This one year double blind randomized placebo controlled trial wasconducted in the Department of Anaesthesia, Narayan Medical College, Jamuhar,Sasaram,Bihar. A total of 60 patients undergoing lower abdominalsurgeries were allocated into two groups namely, Group D (n=30; patientsreceived dexmedetomidine 0.1 mL/Kg [0.5 μg/kg] over 15 minutes using infusionpump 20 minutes prior to SAB) or Group P (n=30; Patients received 0.1 mL/kgnormal saline over 15 minutes using infusion pump 20 minutes prior to SAB). Results In this study, male to female ratio was 0.46:1. Both the groups werecomparable with respect to sex, age, height and weight. No biphasic change inheart rate or mean arterial pressure or significant cardiovascular variability wasobserved after administration of dexmedetomidine. Arterial oxygen saturation inboth groups remained above 97% throughout the study and was comparable inboth groups. The requirement of Atropine and Ephedrine was found to becomparable in both groups. Patients in dexmedetomidine group had asignificantly higher level of highest sensory block level (T4.8±1.52). MotorBlock duration was significantly prolonged in group D (128.00±20.07). SensoryBlock duration in dexmedetomidine group (165.67±19.77) was significantlylonger. Conclusion and interpretation Overall, based on the findings of this study it may be concluded that,single dose of intravenous dexmedetomidine given as premedication, prolongsthe duration of sensory and motor blockade of bupivacaine–induced spinalanaesthesia. It also provides conscious sedation and additional analgesia,maintaining haemodynamic stability.