Spinal anaesthesia is the preferred mode of anaesthesia for infraumbilical surgeries. Levobupivacaine is an isomer of racemic bupivacaine. Various adjuvants have been added to the local anaesthetics to prolong its effect. In present study, we have studied different doses of dexmedetomidine used as an adjuvant to levobupivacaine in spinal anaesthesia. Background: This study aims to investigate the effect of intrathecal administration of different doses of dexmedetomidine on the onset and duration of sensory and motor block, haemodynamic alterations and adverse effects produced by spinal levobupivacaine. Methods: 75ASA I-II patients with age group 18-70 years (weight 50-70 kg) undergoing infraumbilical surgies were randomized to one of the three groups. Every patient received 3.3 ml of drug intrathecally that consisted of 15 mg (3 ml of 0.5%) preservative free levobupivacaine containing either 0.3 ml normal saline (Group L) as control group, dexmedetomidine 15 μg (Group LD1) or dexmedetomidine 30 μg (Group LD2). Onset and duration of sensory and motor block, maximum sensory level achieved, sedation levels, haemodynamic parameters and adverse effects were recorded. Analysis of data between groups was performed using one way analysis of variance test (ANOVA test), student t-test and chi-square test (whichever was applicable). Results: Dexmedetomidine significantly shortens the onset of sensory and motor block and prolonged the time to two segment regression and regression of motor block to modified Bromage 0. In addition group LD2 had higher sedation scores. There was higher incidence of hypotension, bradycardia and respiratory depression in group LD2. Conclusion: Intrathecaldexmedetomidine in a dose of 15 μg significantly prolongs the anaesthetic effects of intrathecallevobupivacaine without significant side effects. So, 15 μg is the preferred dose of dexmedetomidine over 30 μg, when used as an adjuvant to levobupivacaine in spinal anaesthesia.