Coexisting coronary artery disease (CAD) is an important cause of morbidity and mortality in patients with peripheral arterial disease (PAD). Clinical evaluation and noninvasive tests have some important limitations for the detection of CAD in patients with PAD. The purpose of this study was to investigate whether urinary albumin excretion (UAE) was a sign of atherosclerotic involvement of coronary arteries in patients with PAD. Our study consisted of 65 consecutive patients (56 men, 9 women, mean age; 59.7+/-7.9 years) with PAD who underwent coronary angiography. Urinary albumin excretion was measured in 24-hour urine samples by immunoprecipitation technique. PAD was defined as the presence of > or =50% stenotic lesions in at least 1 of the iliac, femoral, popliteal, tibialis anterior, tibialis posterior, or peroneal arteries. CAD was defined as > or =25% diameter stenosis in at least 1 coronary artery. Patients without any coronary lesions were accepted as having normal coronaries. Age, sex, distributions of coronary risk factors, and UAE rates were compared between patients with and without CAD. Mean UAE was 17.9+/-15.6 mg/day in the total population. Thirty-seven percent of patients had CAD, and 63% had no coronary lesion. UAE rates were 22.33+/-18.74 and 15.32+/-13.01 mg/day in patients with CAD and those with normal coronary arteries, respectively (p = 0.021). Microalbuminuria was detected in 25% in patients with CAD and 12% in those without coronary artery lesions (p = 0.184). The difference was not statistically significant. The distributions of other risk factors and sex were not different between the 2 groups. These data suggest that in patients with PAD, urinary albumin excretion rates may be used to determine those with a high probability of CAD. Further studies are required to decide whether this noninvasive testing is appropriate in detecting high-risk patients.