Much has been published on the surgical treatment of leg ischaemia but relatively little is known about the incidence of claudication and the fate of the majority of patients presenting with chronic leg ischaemia who never come to surgery. A review of the available literature suggests the following conclusions: (1) about 1.5% of men under 49 and 5% of men over 50 will develop symptoms of intermittent claudication. The incidence of asymptomatic arterial disease is much higher; (2) the incidence of claudication in women is only slightly less, but the local disease follows a more benign course; (3) compared to the general population of comparable age the mortality of men presenting with chronic leg ischaemia is two to three times higher after 5 years; (4) about 50% of deaths will be due to myocardial ischaemia, 15% to stroke and 10% to vascular disease in the abdomen. In only 25% will the principal cause of death be unconnected with the circulation; (5) there is virtually no reliable information available at the moment on the incidence of non-fatal myocardial infarction or stroke in these patients.