Background: The transversus abdominis plane (TAP) block is a regional analgesia technique that forms part of the multimodal approach to post-operative pain management for abdominal surgeries. Local anesthetics like Bupivacaine with longer duration are preferred for TAP block. Objectives: To evaluate if Fentanyl as an adjuvant to bupivacaine in ultrasound guided TAP block improve the duration and quality of post-operative analgesia following abdominal hysterectomy. Methods: Forty four patients, aged 18–60 years of American Society of Anesthesiologist (ASA) Physical status I or II, posted for elective open abdominal hysterectomy under general anesthesia were recruited by convenience sampling technique, to receive TAP block using 19.5 ml of bupivacaine hydrochloride 0.25% + 0.5 ml saline 0.9% (Group B, n = 22) or 19.5 ml of bupivacaine hydrochloride 0.25% + 0.5 ml Fentanyl. (25 micrograms) (Group BF, n = 22), after the completion of surgery but prior to extubation. Visual analog scale (VAS) scores at rest and movement were assessed on the emergence, at 0, 2, 4, 6, 12 and 24 hours (h). Results: VAS score was significantly lower in study group, at rest at 2h (14.68 vs 20.63, p = 0.006), 4h (24.46 vs 24.77, p = 0.02), 6h (22.27 vs 28.45, p = 0.002) and 12h (18.90 vs 21.00, p = 0.043) and that with movement, at 2h (20.45 vs 25.86, p = 0.006), 4h (25.23 vs 30.95, p = 0.001) and 6h (29.14 vs 33.90, p = 0.006). Sedation score in study group was relatively significant at 4h (1.77 vs 1.27, p = 0.01) but clinically in-significant to cause major adverse effects. Conclusion: Fentanyl as an adjuvant to bupivacaine in ultrasound guided transversus abdominis plane block, following abdominal hysterectomy under general anesthesia improves the quality and duration of post-operative analgesia without any major adverse effects.