This study investigated the population prevalence of chronic arterial occlusion (CAO) using the ankle pressure index (API) of patients with lower back pain in an acupuncture clinic. The API was measured in 60 lumbago patients ≥ 50 years old at the Meiji College of Oriental Medicine Acupuncture Center. There were 19 patients (31.7%) with unilateral or bilateral API < 0.9, which was presumed to indicate CAO. Thirty-four patients had symptoms in the lower limbs, and 17 of 34 patients showed an API below 0.9. In all but 4 patients (13 of 17, or 76.5%), laterality of the lower API and the symptoms were noted. In conclusion, API measured noninvasively might be useful as a predictor of CAO in acupuncture clinics.