A 49-year-old man was hospitalized for slight paresis of the upper left limb. Thrombosis of the right internal carotid artery was documented by arteriography and digital angiography, which showed evidence of an anastomotic blood flow. He went on anticoagulation treatment. Five years later, after an uneventful period, he was referred to our center for the occurrence of a superficial thrombophlebitis: diagnosis of congenital protein C deficiency was possible in the patient as well as in two of his relatives. Two other subjects with congenital protein C deficiency belonging to two different kindreds, whose illness was diagnosed in our center, suffered from myocardial infarction and TIA, respectively, as the only clinical manifestation; a fourth case, previously described, with recurrent superficial thrombophlebitis, suffered from a TIA when on treatment with stanozolol. These cases indicate that arterial thrombosis or TIA is not an uncommon event in congenital protein C deficiency, even in patients without other risk factors for arterial thrombosis.