An 11-year-old boy with Lesch–Nyhan syndrome presented to the emergency for fixation of a fractured femur. During induction of general anesthesia, unexpected difficult intubation was encountered with a 6.5-mm ID endotracheal tube and successively smaller tubes, also failing to pass 1 cm beyond the vocal cords. Intubation was finally achieved with a 4.5-mm ID tube. The surgery was completed uneventfully. A tracheal diverticulum was found in the computerized tomography (CT) scan performed postoperatively to account for this unexpected difficult intubation. This case highlights the anesthetic concerns in Lesch-Nyhan syndrome and also reports the rare occurrence of a tracheal diverticulum associated with it.