Background: Spinal anesthesia has always had problems with the timing of the onset and the length of the motor and sensory block. By combining local anesthetics with an adjuvant, one can lengthen the block's effect and lessen its side effects. In this study, patients undergoing elective infra-umbilical surgeries were given 25mcg/50mcg of neostigmine in addition to bupivacaine and the efficacy was studied. Aims: The assessment and comparison of: Onset of the Sensory Blockade Duration of the Sensory Blockade, Onset of the motor blockade, Duration of the motor blockade, Adverse effects. Materials and Methods: About 60 patients scheduled for elective infra-umbilical surgeries under spinal anesthesia were enrolled in our study. One of the three groups (each with 20 patients) was randomly assigned to patients: Group BS: Hyperbaric 0.5% Bupivacaine 3ml+0.5mL Normal Saline, Group BN 25: Hyperbaric 0.5% Bupivacaine 3mL+25mcg Neostigmine (0.5 mL), Group BN 50: Hyperbaric 0.5% Bupivacaine 3mL+50mcg Neostigmine (0.5 mL). The onset of anesthesia, duration of postoperative analgesia, time to use first rescue analgesia, overall, 24-hr VAS pain scores, are recorded for 24-hr post drug administration. Intra operative and postoperative blood pressure, heart rate, oxygen saturation, incidence of adverse effects and the total amount of analgesic consumed in overall 24-hr were recorded. Results: The duration of sensory and motor block was significantly prolonged with addition of 25mcg/50 mcg neostigmine to Bupivacaine for patients undergoing infra-umbilical surgeries under spinal anesthesia. It might cause a delay in attaining the discharge criteria in day care surgeries and there was a dose-dependent increase in the severity of nausea, vomiting with the highest PONV score in the group of patients who received 50mcg of neostigmine along with Bupivacaine intrathecally. Conclusion: Intrathecally administered doses of 25mcg or 50mcg neostigmine and Bupivacaine increased the duration of sensory and motor block, reduced the need for rescue analgesia and delayed postoperative pain for 5–6hours.Hense we recommend the addition of 25mcg of Neostigmine to Bupivacaine for Spinal anesthesia with minimal adverse effects.