Background: Spinal anesthesia is the most common method of the regional block in cesarean section, because it is easy to perform, economical produces rapid onset of anesthesia, and good muscle relaxation, and most importantly, it gives immense pleasure to the conscious mother. To improve the quality of subarachnoid block, intrathecal opioids are used as adjuvants to Bupivacaine. Fentanyl has a rapid onset of action as a lipophilic opioid following intrathecal administration. Because of high lipid solubility, it undergoes rapid uptake by the spinal cord, and hence the chances of delayed respiratory depression are less. Methods: We randomly selected 60 patients belonging to the American Society of Anesthesiologists (ASA) class I and II, who are scheduled for elective LSCS. These patients were divided randomly into two groups of 30 each. Group B received 10mg of 0.5% hyperbaric bupivacaine (2ml). Group BF received 7.5mg of 0.5% hyperbaric bupivacaine (1.5ml) with 25mcg of Fentanyl (0.5ml). Lumbar puncture was performed at the level of L3-L4 with 23 Guage Quincke Babcock's needle with the patient in the right lateral position. The sensory block was assessed with the loss of pin prick sensation, and the motor block was set using the Bromage scale technique. We also recorded the hemodynamic parameters like pulse rate, blood pressure, oxygen saturation. Results: No significant statistical difference was found in demographic data between the two groups. Group BF showed early onset of the sensory block with a P value of 0.001. Time taken to attain peak sensory level was early in the BF group with a P value of 0.001. The total duration of sensory block and duration of effective analgesia was longer in the BF group with a P value of 0.001. The onset of motor blockade was early in the bupivacaine only group with a P value of 0.02. Conclusion: The intrathecal fentanyl 25mcg reduces the dose of 7.5 mg of 0.5% hyperbaric Bupivacaine for spinal anesthesia in cesarean section, thus reducing the incidence of side effects associated with it. By its synergistic effect with 0.5% hyperbaric bupivacaine, it provides better excellent sensory blockade and postoperative analgesia, good hemodynamic stability, less incidence of complications like Nausea, vomiting, and shivering without compromising the safety of mother and fetus in comparison to intrathecal 10mg of 0.5% hyperbaric Bupivacaine alone.