Sublingual (SL) buprenorphine is approved for managing acute postoperative pain, characterized by easy administration, good pain relief and good patient compliance. We hypothesized that SL buprenorphine would be a better perioperative analgesic compared to intravenous (IV) opioids like tramadol in patients undergoing mastectomy surgery for breast cancer. After institutional ethics committee approval, we randomized 60 patients with breast cancer into 2 groups. In buprenorphine group, patients received 200 μg of SL buprenorphine thrice daily and in tramadol group patients received 100 mg of IV tramadol thrice daily. The analgesic efficacy of SL buprenorphine was comparable to that of IV tramadol. Visual Analogue Scale scores had no significant difference between the two groups at various time frames (0, 1, 3, 6, 12, 18 and 24 hours) at rest and movement except at 0 and 3 hours during movement when the score was lower in the tramadol group than the buprenorphine group. Four patients in the buprenorphine group received rescue analgesic (IV morphine 3 mg). Analgesic efficacy of SL buprenorphine appears comparable to IV tramadol for managing postoperative pain after mastectomy. SL buprenorphine can be administered sublingually, which is an advantage.