A 33-year old man developed progressive intracranial hypertension with papilloedema due to thrombosis of the superior sagittal sinus (SSS) by extension of a skull osteitis. Serological tests for syphilis were positive in blood, CSF and synovial fluid. Under treatment with penicillin and corticosteroids signs of intracranial hypertension and CT scan abnormalities disappeared. SSS thrombosis persisted at angiographic control.