We report a case of a penetrating cranio-facial injury due to a nail-gun accident. An 18-year-old worker was admitted to our hospital as an emergency patient. He was working using a nail-gun when a nail ricocheted off a wall and pierced the right side of his face. Skull X-rays and a CT scan showed that a 9 cm nail had pierced his right frontal lobe through the right maxillary bone via the orbital space. The patient was alert without any neurologically abnormal findings. A small stab wound was recognized on his face. The nail was removed six hours after the injury through a sublabial approach and a fronto-temporal craniotomy. The nail was very tightly fixed in the maxillary bone and skull base bones, and a screw driver normally used in orthopedic surgery proved to be very useful for removing the nail. The patient returned home 14 days later without any neurological deficits. The technical problems associated with such a nail-gun injury in the face and skull are also discussed.