An increasing proportion of patients with lower limb arterial disease are being treated by transluminal angioplasty. There have been various estimates of the numbers of potentially treatable patients, but none have been accompanied by detailed selection criteria. Based on patients' arteriograms, we present a clear grading system of suitability for angioplasty aimed at allowing ready interpretation and comparison of data. We have used these grades to examine prospectively the suitability for angioplasty of 118 consecutive patients undergoing arteriography for the first time. Thirty-five per cent of patients with claudication, and 30% of those with rest pain or trophic lesions appeared suitable for angioplasty. Forty-five per cent of claudicants and 40% patients with rest pain or trophic lesions could have their symptoms relieved by appropriate angioplasty of aortoiliac disease alone in the presence of distal disease, or of isolated femoropopliteal lesions. These figures have important implications for the provision of interventional radiological services throughout the United Kingdom.