This article discusses physiological diagnostic methods in the intractable vasculitis, including Buerger's, Takayasu's and vasculo-Behçet disease. Clinical manifestations of these diseases depend on the lesions of the diseased arteries or veins such as obstruction of the extremities often occurring in Buerger's disease, the obstruction of aortic arch branches in Takayasu's disease and the deep vein thrombosis in vasculo-Behçet disease. Measurements of segmental blood pressure and flow allows a detection of peripheral vascular disease and non-invasive diagnostic techniques, such as the doppler ultrasonic techniques and strain-gauze plethysmography, permit accurate evaluation of arterial occlusive disease and estimation of its physiological significance. Noninvasive diagnostic techniques, together with clinical symptoms and physical examinations, make possible correct diagnosis and subsequently appropriate treatment.