Neurologic hemisyndromes in childhood may be due to congenital or acquired changes in cerebral vessels. Among the congenital vascular malformations, which very rarely become manifest already in children, the arteriovenous angiomata and saccular aneurysms are relatively the most common (in childhood about 4-8% manifest, 1-2% of all diseases). Venous angiomata, micro-angiomata and congenital dissecting aneurysms are very rare. But acquired thrombotic blocks of cerebral arteries are of greater importance as causes of acute neurologic hemisyndromes in childhood. Most often they have an inflammatory or traumatic cause, often the cause is unknown. Rare diseases only very recently described as arterial blocks of cerebral vessels are fibromuscular dysplasia and Moya-Moya-disease, the etiology of which is not yet fully understood. The prognosis of these diseases is generally unfavorable, but the focal signs in migraine as visual, sensory, aphasic and motoric defector irritative signs are as a rule reversible. In order to establish, where possible, the cause of acute neurologic hemisyndromes in childhood, early angiography may-classic migraine accompagnee types excepted-help. But also modern biochemical, immunologic, virologic, serologic, bacteriologic, clotting analytic and, possibly, histologic and histochemical techniques should be employed with particular attention to fat metabolism and to auto-immune disease.