In 1095 patients 2770 brain supplying arteries have been studied by i.a.-DSA. Definitive neurological deficits occurred in 0.09%, transient deficits were observed in 0.45%. The reduced complication rate in comparison to former studies seems to be a continued effect of technical progress (DSA) and the use of new isoosmotic contrast media. In order to reduce the "training hospital effect" as to complication rate careful supervision of trainees is necessary. The average fluoroscopy time per vessel is proposed as an objective measure of the investigational skill of a neuroradiologist.