Diseases of the terminal vascular system are of particular diagnostic and differential-diagnostic importance in clinical angiology. While in the functional microangiopathies of the skin as a rule disturbances of the vasomotor function without an essential value of the disease are concerned, secondary organic changes of the wall of the vessel not infrequently determine the course and the prognosis of the basic disease (rheumatoid arthritis, collagenoses, hypertension and diabetes). Vasomotor trophic disturbances are observed also post-traumatically, post-operatively, after exposition to cold, in a lesion of the central nervous system and vertebra nerve irritations. For the allergic hyperergic vasculitides, which show an extraordinary polymorphism in the clinical picture in characteristic histological findings, an auto-immune pathogenesis is to be supposed. The chronic arterial hypertension leads to arteriolosclerosis and necrosis with adequate organic symptoms. In the diabetic microangiopathy we may demarcate functional pre-stages from irreversible structural changes of the vessels, in which case apart from the peripheral microangiopathy of the skin the retinopathy and nephropathy are to be classified as particularly important clinical manifestations.