In the order Hymenoptera, bees, hornets, and wasps are well-known stinging insects whose envenoming can be fatal. Their stinging attacks are common in rural and forested areas of Sri Lanka. However, fatal stinging by the large-bodied carpenter bees is unreported. We report the first known case of a fatal sting by the large carpenter bee, Xylocopa tranquebarica, in a forested area in Puttalam (North Western Province) in the dry zone of Sri Lanka. A 59-year-old healthy male manual laborer accompanied by a fellow worker had been fixing a fence on a coconut estate bordering a forested area when a flying insect emerged from a dead tree trunk and stung him on his face. His coworker, who was watching the incident, killed the insect. The victim complained of immediate intense pain in the face and collapsed on the ground just after resuming work after 10 minutes of resting. He was found dead on admission to the hospital 90 minutes later. Autopsy showed normal coronary arteries and heart, but the lungs were slightly congested and contained secretions in the bronchi. Acute anaphylaxis was the most likely cause of death. This case presents the habitat, morphology, attack pattern, and the medical importance of large carpenter bees.