Renal insufficiency predicts mortality among patients who are treated for myocardial infarction and congestive heart failure, but its clinical significance in advanced peripheral arterial disease has not been evaluated. A national cohort of 5787 male veterans who received an initial diagnosis of rest pain, ischemic ulceration, or gangrene between January 1, 2000, and September 30, 2002, and had at least one serum creatinine measurement within 3 mo before diagnosis were identified. Sixty-two percent (n = 3561) of cohort members had normal or mildly reduced renal function (GFR > or =60 ml/min per 1.73 m(2)), 30% (n = 1742) had moderate renal insufficiency (GFR 30 to 59 ml/min per 1.73 m(2)), and 8% (n = 484) had severe renal insufficiency or renal failure (GFR <30 ml/min per 1.73 m(2)) but were not on dialysis. The percentages of patients who presented with gangrene or ischemic ulceration rather than rest pain increased with declining renal function (70, 77, and 87%; P < 0.001), as did 1-yr mortality risk (17, 27, and 44%; P < 0.001). After adjustment for demographic and clinical characteristics, patients with a GFR of 30 to 59 ml/min per 1.73 m(2) (odds ratio, 1.32; 95% confidence interval, 1.13 to 1.53) and <30 ml/min per 1.73 m(2) (odds ratio, 2.97; 95% confidence interval, 2.39 to 3.69) had a significantly increased odds of death within 1 yr of cohort entry. Both moderate and severe renal insufficiency are associated with an increased odds of death in patients with critical limb ischemia. Death rates were particularly high among those with a GFR <30 ml/min per 1.73 m(2). This finding may be partly explained by their more frequent presentation with ischemic ulceration or gangrene rather than rest pain.