Chronic kidney disease (CKD), defined by either microalbuminuria (MA) or a reduced estimated glomerular filtration rate (eGFR), is associated with an increased risk of peripheral arterial disease (PAD). The presence of both abnormalities might identify a subgroup of adults at particularly high risk of PAD. Accordingly, we sought to evaluate the combined effect of a reduced eGFR and MA on the prevalence of PAD among United States adults. United States adults >or=40 years old (n = 6,951) participating in the 1999 to 2004 National Health and Nutrition Examination Survey were cross-classified into 4 groups according to the presence or absence of MA (urinary albumin/creatinine ratio >or=30 mg/g) and reduced eGFR (<60 mL/min/1.73 m(2)). PAD was defined as an ankle-brachial index of <0.9. The prevalence of PAD among adults without MA or a reduced eGFR was 3.6% compared to 9.7%, 14.8%, and 25.4% among adults with MA alone, reduced eGFR alone, and both reduced eGFR and MA, respectively. After multivariate adjustment, the odds ratio for prevalent PAD associated with MA alone, reduced eGFR alone, and both reduced eGFR and MA compared to those without MA or reduced eGFR was 1.72 (95% confidence interval 1.16 to 2.55), 1.58 (95% confidence interval 1.09 to 2.29), and 2.26 (95% confidence interval 1.30 to 3.94), respectively. In conclusion, the coexistence of MA and reduced eGFR was associated with a high prevalence of PAD and might be useful in identifying patients with vascular disease.