The arterial wall stiffness in the common femoral artery was determined by means of an ultrasound technique in 47 insulin-dependent diabetics and 24 controls aged 20 to 39 years. They were all without vascular symptoms and signs, and were selected in such a way that they were thought to be free of age correlated changes. Furthermore, patients in potential risk groups, as for arterial disease of non-diabetic type, were excluded. The arterial wall stiffness was significantly increased in the diabetic group as compared with a control group. Furthermore, there was a significant correlation to the diabetic duration. Possible pathogenetic reasons are discussed.