Carotid artery injury is a very rare, but life threatening complication that can occur during a transsphenoidal approach. We experienced one case of carotid artery injury during a transsphenoidal pituitary tumor surgery. The patient was immediately treated by a balloon occlusion and complete packing of the cavernous carotid artery using Guglielmi detachable coils (GDCs) and the rest of the tumor was removed after the carotid occlusion. The patient recovered without showing any neurological deficits.