Objectives To determine the prevalence of cognitive impairment in older adults with heart failure (HF). Design Cross-sectional analysis of the 2004 wave of the nationally representative Health and Retirement Study linked to 2002 to 2004 Medicare administrative claims. Setting United States, community. Participants Six thousand one hundred eighty-nine individuals aged 67 and older. Measurements An algorithm was developed using a combination of self- and proxy report of a heart problem and the presence of one or more Medicare claims in administrative files using standard HF diagnostic codes. On the basis of the algorithm, three categories were created to characterize the likelihood of a HF diagnosis: high or moderate probability of HF, low probability of HF, and no HF. Cognitive function was assessed using a screening measure of cognitive function or according to proxy rating. Age-adjusted prevalence estimates of cognitive impairment were calculated for the three groups. Results The prevalence of cognitive impairment consistent with dementia in older adults with HF was 15%, and the prevalence of mild cognitive impairment was 24%. The odds of dementia in those with HF were significantly higher, even after adjustment for age, education level, net worth, and prior stroke (odds ratio = 1.52, 95% confidence interval = 1.14?2.02). Conclusion Cognitive impairment is common in older adults with HF and is independently associated with risk of dementia. A cognitive assessment should be routinely incorporated into HF-focused models of care.