Clinical data of 19 arteriovenous malformations (AVM) and 15 aneurysms (AN) are presented. Combined clinical, neurophysiological and neuroradiological follow-up studies have been carried out on the surviving patients (14 AVM and 10 AN). Two patients with multiple AN had coarctation of the aorta. Three AVM of the Vein of Galen showed typical symptoms within the 1st year of life, all other lesions became evident later than 5 years of age. In the acute phase of the disease clinical history and neurological deficits of AVM and AN tend to be very similar. Subarachnoid hemorrhage with or without intracranial hematoma is the most frequent initial symptom. A CT scan is valuable as a first orientating investigation but morphology and operability of the vascular lesion is only demonstrated by angiography. The prognosis of AVM and AN is promising as soon as the first critical period has been survived. AVM patients show significantly less severe residual neurological and psychiatric defects than AN cases. EEG-follow-up studies and CT scans are helpful for controlling residual functional and morphological cerebral damage in survivors.