Forty-four patients with operatively created arteriovenous fistulas have been examined angiographically. Widening of the main arteries of the forearm was evident, the most pronounced widening occurring in the artery feeding the fistula. Stenosis of the arteries or veins seldom influenced the flow significantly. Blood from the fistula was often partly or totally directed into the hand. In nine patients filling of deep veins was evident, and in most of these cases big fistulas were present. A rough estimate of the blood supply to the hand indicated poor supply in eight patients of which only one had symptoms of ischemia. Brachial angiography is of value in estimation of the blood flow in fistulas, when cannulation of veins is difficult, when thrombosis is suspected, or when a new fistula is planned after decreased function of an old one.