Background: Tonsillectomy is one of the most common surgeries in the world which is followed by severe post-operative pain. The concept of using bupivacaine as pre-emptive analgesic to minimize post-operative pain is a well-established by some surgeons. But the role of bupivacaine to decrease post tonsillectomy pain is still viewed with some degree of suspicion by other otolaryngologists. Objective: To determine the effect of preincisional bupivacaine 0.25% infiltration on post-tonsillectomy pain. Materials and Methods: A prospective, randomized control trial was performed during a period from June 2015 to November 2015, 60 patients who underwent tonsillectomy were divided into two equal groups. The first group (A): who received infiltration of bupivacaine, and the second group (B): who received placebo infiltration of saline. Pain scores were assessed postoperatively using a visual analogue scale (VAS) at 1, 4, 8 and 24 hours after the procedure. Results: According to our statistical analysis and data, the reduction in pain at 1 (P=0.214) hour in group A was statistically insignificant compared with group B. However, at 4 (P=0.002), 8 (P=0.000), and 24 (P=0.001) hours post-operatively, the reduction of pain in group A was statistically significant compared with group B. Conclusion: Injection of plain bupivacaine solution in a 0.25% concentration just 5 minutes before surgery appears to be effective in reducing post-tonsillectomy pain within the first 24 hours.