Angiotensin-converting enzyme inhibitors and angiotensin II-receptor antagonists are recommended for patients with chronic kidney disease because these drugs can slow disease progression. Older adults account for a large and growing number of patients with chronic kidney disease. The authors evaluated the relevance to adults older than 70 years of the evidence base for major U.S. practice guidelines for the use of these agents in chronic kidney disease. The authors first examined the representation of older adults in randomized trials that underpin these guidelines, then compared the characteristics of participants in these trials with those of a representative sample of older adults with chronic kidney disease in the general population. The authors found that current guidelines for the use of angiotensin-converting enzyme inhibitors and angiotensin II-receptor antagonists in chronic kidney disease are based on evidence with limited relevance to most persons older than 70 years with this condition.