Background and objectives: It has been suggested that reduced estimated GFR (eGFR) among older adults does not necessarily reflect a pathologic phenomenon. Design, setting, participants, & measurements: We examined the association between eGFR and albumin-to-creatinine ratio (ACR) and all-cause mortality stratified by age (45 to 59.9, 60 to 69.9, 70 to 79.9, and ≥80 years) among 24,350 U.S. adults in the population-based REasons for Geographic and Racial Differences in Stroke (REGARDS) study. A spot urine sample was used to calculate ACR, and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation was used to calculate eGFR. All-cause mortality was assessed over a median follow-up of 4.5 years. Results: Among participants ≥80 years of age (n = 1669), the age, race, gender, and geographic region of residence adjusted hazard ratios (95% confidence intervals) for mortality associated with eGFR levels of 45 to 59.9 and <45 ml/min per 1.73 m 2, versus ≥60 ml/min per 1.73 m 2, were 1.6 (1.3 - 2.1) and 2.2 (1.7 - 2.9), respectively. Also, among participants ≥80 years of age, the hazard ratios for mortality associated with ACR levels of 10 to 29.9, 30 to 299.9, and ≥300 mg/g, versus <10 mg/g, were 1.7 (1.3 - 2.1), 2.5 (1.9 - 3.3), and 5.1 (3.6 - 7.4), respectively. These associations were present after further multivariable adjustment and within the younger age groupings studied. Conclusions: These data suggest that reduced eGFR and albuminuria confer an increased risk for mortality in all age groups, including adults ≥80 years of age. © 2011 by the American Society of Nephrology.