A 51-year-old woman with bone wax-induced osteohypertrophy presented with exophthalmos 9 years after a craniotomy for a right internal carotid bifurcation aneurysm. CT scans revealed thickening of the frontotemporal bone flap and surrounding bone, thickening of the upper and lateral orbital walls, and a limited intraorbital cavity. Intraoperative findings revealed residual bone wax under the bone flap, grayish-white discoloration of the flap, and degeneration of the temporal muscle. Pathological examination revealed granulation and osteogenesis due to a foreign body. To our knowledge, this is the first report of bone wax-induced hyperostosis leading to exophthalmos.