Arteriosclerosis is the most common cause of peripheral arterial disease (PAD); it begins in the second and third decades of life but first becomes manifest, however, many years later. The hemodynamic effects of arterial narrowing in the peripheral arteries are dependent on functional and morphological adaption, temporal and topographical factors and the prevailing metabolism. In the large arteries of the legs, luminal narrowing of more than 70% is required to render impairment of normal exercise capacity such that it can be assumed that even substantial vascular changes may not be associated with clinical symptoms. An acute peripheral vascular occlusion is regarded as a medical emergency. The most frequent cause is in-situ thrombosis or embolism; the most common sources of embolism are valvular lesions in the left side of the heart and thrombi in the left ventricle after myocardial infarction. Sites of predilection for emboli are acutely-angled branching points of arteries primarily in the lower extremities (aorta, iliac, femoral and popliteal arteries). With the exception of the deep femoral artery, the statement is generally valid that the more central the occlusion, the more severe are the effects anticipated. In-situ arterial thrombosis superimposed on a preexistent arteriosclerotic stenosis or after vascular reconstruction, leads to occlusions generally in the pelvic region or upper thigh. Further causes of acute local vascular occlusion are pressure, tension or kinking at the artery, rarely trauma, dissecting aneurysm or ergotism. In 90% of patients with PAD there is involvement of the lower extremity, apparently due to the effects of hydrostatic pressure. Three types of disease can be differentiated: the pelvic type which is observed in approximately one-third of all cases. Through occlusion of the distal aorta (Leriche syndrome) or the large iliac vessels, vice-like pain is incurred in the hip musculature which frequently radiates to the upper thighs; with bilateral occlusion, impotence develops.(ABSTRACT TRUNCATED AT 250 WORDS)