A 30-year old man suffered a frontobasal injury type I, according to Escher an extensive high frontobasal fracture. According to the classification of gunshot wounds it was an open intracranial injury with damage of the dura mater caused by a slow projectile with low energy. The projectile struck the frontal region where it caused a lacerated skin wound. The patient was not unconscious. He attended for definite treatment only on the 8th day after the injury. He had no complaints, did not have an apparent cosmetic defect and did not have obvious liquorrhoea not even after provocation manoeuvres. Superficial examination could have led to quite incorrect conserva- tive treatment. Only CT examination revealed a comminuted fracture of the anterior and posterior wall of the frontal sinuses with intracranial impression of the fragments. Except for a minor pneumocephalus there were no signs of brain damage. Examination of the nasal secretion for beta transferrin revealed nasal liquorrhoea. Indication for surgery was a bone fragment detected by CT which penetrated the brain about 1 cm deep, and nasal liquorrhoea detected by laboratory tests. This finding threatened to be a late life endangering complication. The patient was submitted to surgery on the 13th day after the injury. A bicoronary section was done and access to intracranium was made via the bone defect - cranialization of the frontal sinuses, plastic operation of the dura mater by a free pericranial flap and plastic operation of the anterior wall of the sinuses by a bone graft from the external lamina of the calva. The surgical finding confirmed the serious character of the injury and the necessity of a surgical approach.

        Key words: injury of the frontal sinus, nasal liquorrhoea, cranialization, calvar graft.