Background: Cognitive dysfunction has a major role in health outcomes for cardiac patients. The association of cognitive dysfunction with heart failure is well established, but the cardiac variables that contribute to cognition are not well understood. Objectives: To investigate the relationships among age, memory, and left ventricular ejection fraction (EF) in patients with heart failure. Design: Retrospective study. Setting: Academic medical center. Participants: A total of 207 patients with heart failure underwent neuropsychological assessment of memory on standardized tests. Main Outcome Measures: Patients were grouped by age quartiles, and memory function was compared in those with an EF below 30% vs those with an EF of 30% or higher. Results: Demographic, cognitive, and medical variables having a significant association with a memory composite score were identified in a univariate linear regression analysis. In a multivariate linear model that adjusted for significant covariates, there was a significant interaction between age and EF for memory function. Patients younger than 63 years maintained stable memory function across EF levels, but patients 63 years or older showed a significant decline in memory performance when EF dropped below 30% (P<.02). Post hoc multivariate analysis showed that verbal delayed recall and recognition were the components of memory most affected by low EF. Conclusion: The effect of EF on memory differs by age such that older patients with lower EFs have significantly reduced verbal memory function. ©2011 American Medical Association. All rights reserved.