Objectives: This study aims to compare the effects of intrathecal administration of hyperbaric bupivacaine premixed with fentanyl versus sequential administration of the two in separate syringes in lower limb surgeries on block characteristics. Fentanyl is a lipid soluble opioid commonly used as adjuvant to local anaesthetic. It provides a stable hemodynamic profile and prolonged analgesia. The primary outcome of this study was the onset and duration of sensory and motor block. Secondary outcomes were degree of motor block, hemodynamic parameters, sedation score and adverse effects. Methods & Materials: A total of 60 patients were randomly assigned to two groups, each consisting of 30 patients. In Group P, patient received 2.5ml of 0.5% heavy bupivacaine (2.5 ml or 12.5 mg) mixed with 0.5 ml (25 micrograms) of fentanyl in 3ml syringe. Group S received 2.5 ml (12.5 mg) of 0.5% heavy bupivacaine in a 3.0 ml syringe, followed by 0.5 ml (25 micrograms) of fentanyl in another 3.0 ml syringe. Statistical calculations performed using the SPSS 21 version statistical program for Microsoft Windows. Results: In terms of the onset of sensory and motor block, group S exhibited the short duration, compared to group P. Group S demonstrated prolonged sensory and motor block durations. Group P experienced a higher incidence of hypotension compared to groups S. In conclusion, administering hyperbaric bupivacaine prior to fentanyl resulted in an earlier onset and longer duration of sensory and motor block. Conclusions: The sequential administration of hyperbaric bupivacaine followed by fentanyl leads to an accelerated onset and extended duration of sensory and motor block.