A case of partially occluding post-traumatic thrombosis of the internal carotid artery and secondary embolism of the middle cerebral artery is reported. The patient was treated with Thrombolysin with coincident resolution of clinical symptoms and signs and clearing of the lesions on arteriography. This may have been fortuitous. The subject of traumatic carotid artery thrombosis is reviewed in detail, and its pathophysiology is discussed, especially in relation to facts known about occlusive vascular disease secondary to atherosclerosis and related embolic phenomena. Suggestions are made concerning the treatment of this condition, especially with regard to developing rational criteria for opening vascular beds through evaluation of collateral cerebral blood flow. The uses of microvascular surgical techniques and thrombolytic therapy are considered.