We examined the prevalence of peripheral arterial disease (PAD) in Japanese diabetic patients with ankle–brachial index (ABI). Outpatients with diabetes (n=4249) who were regularly visiting Kyushu University Hospital, its 17 related hospitals, Ryukyu University Hospital and its 6 related hospitals were enrolled in the Kyushu Prevention Study for Atherosclerosis from 2001 to 2003. At baseline, ABI was measured using a device “form PWV/ABI”. Valid information was available for 3906 diabetic patients (mean age: 60.8 years) including 1612 elderly patients (>65 years). Patients with a low ABI (<0.9) on either side or on both sides were considered to have PAD. The prevalence of PAD patients with ABI<0.9 was 7.6% in all diabetic subjects. Elderly patients (>65 years) had a higher prevalence of PAD (12.7%) compared with younger patients (<65 years) (4.0%). In addition, the rate of patients who had been diagnosed accurately as having PAD before enrollment was low (24.4%). The prevalence of PAD was high in Japanese patients with diabetes, especially in elderly patients, in contrast to low rates of accurate diagnosis. Better diagnostic efforts and more intensive treatments are needed to improve quality of life and the overall prognosis of life in Japanese diabetic patients.