Background: A Modified Radical Mastectomy is a surgical procedure that involves the removal of breast tissue, along with some of the surrounding lymph nodes, in the treatment of breast cancer. The present study was conducted to evaluate post-operative analgesia in modified radical mastectomy patients using surgical wound irrigation with 0.25% bupivacaine. Materials & Methods: 50 women undergoing modified radical mastectomywere divided into 2 groups of 25 each. In group I, before closure of the wound, a 20G scalp vein set was used along the length of the incision with multiple punctures in it for continuous irrigation with 0.25% bupivacaine. In group II, the routine post-operative pain management was followed. Post-operatively, visual analogue scale was used to measure the pain sensation at every six hours for 24 hours. Results: The mean duration of surgery (min) was 152.4 and 158.4, fentanyl dose infused (µg) was 115.4 and 113.2 and the number of rescue analgesia doses needed in 24 hours was 0.51 and 2.18 in group I and II respectively. The difference was significant (P< 0.05). The mean VAS at 0 hours was 0.42 and 11.12, at 6 hours was 0.49 and 2.235, at 12 hours was 0.63 and 4.31, at 18 hours was 0.72 and 3.17 and at 24 hours was 0.40 and 1.74 in group I and II respectively. The difference was significant (P< 0.05). Conclusion: Irrigation of wound with 0.25% Bupivacaine is found to reduce the pain sensation in modified radical mastectomy cases.