Skull films of 5,570 patients older than 40 years of age admitted to the neurological (4,308), ophthalmologic (1,151), and otorhinolaryngologic clinics (111) of the University of Milan over a period of 20 years were reviewed for carotid siphon calcification. The 485 positive findings were divided into intimal and medial calcifications on the basis of morphological criteria. Signs of cerebrovascular disease in the territory of the internal carotid artery were seen in 35.1% of the intimal group and 37.2% of the medial group. These findings suggest that the two types of calcification do not have different prognostic values as theorized previously.