BACKGROUND: Peripheral artery disease (PAD) represents a common manifestation of systemic atherosclerosis that is associated with an increased risk of cardiovascular death and ischemic events but one that may be underdiagnosed in clinical practice. The purpose of this study was to identify PAD using the ankle-brachial index (ABI) in hospitalized patients from a Department of Internal Medicine and to further investigate the association of this index with traditional cardiovascular risk factors. METHODS: We measured ABI in 990 consecutive patients (400 men and 590 women) aged 50 years or older (71.2+/-9.1) without a history or symptoms suggestive of PAD. ABI values below 0.90 were considered abnormal. RESULTS: PAD was detected in 356 patients (36%), and men had a higher prevalence than women (p<0.001). Hypertension (p<0.001), smoking (p<0.001), diabetes (p<0.05), male sex (p<0.001), and dyslipidemia (p<0.05) were statistically more frequent in patients with PAD, whereas obesity had no significant relation to PAD in our series. In a stepwise, logistic regression analysis, hypertension, male sex, diabetes mellitus, smoking, and dyslipidemia were found to be independent risk factors with odds ratios (95% confidence intervals) of 2.46 (1.85-3.27), 2.25 (1.66-3.05), 1.80 (1.32-2.47), 1.78 (1.31-2.42), and 1.64 (1.22-2.19), respectively. CONCLUSIONS: A simple ABI measurement revealed a large number of patients with unrecognized PAD. It is, therefore, recommended that ABI measurement should be included in the evaluation of cardiovascular risk in hospitalized patients aged 50 years or older.