Introduction: Approximately 25% to 75% of heart failure (HF) patients have sleep apnea (SA), which may contribute to brain changes that are associated with decreases in attention, memory, and executive function. Unfortunately, there is a dearth of research that explores how SA may contribute to brain changes and cognition within the HF population. Thus, the purpose of this study is to examine the relationships between the apnea-hypopnea index (AHI), grey and white matter brain volumes, and neuropsychological test scores of attention, memory and executive function. Hypothesis: HF patients with higher AHI would have decreased brain volumes and neuropsychological test scores. Methods: Using a cross-sectional design, we sampled 28 HF patients; 13 HF patients had AHI ≥ 10 and 15 HF patients had AHI <10. Eighty percent were male (n=12) and their mean age was 68 (SD = 5). We evaluated AHI with a portable multichannel sleep-monitoring device, brain volumes with voxel-based morphometry method T-1 weighted images from 3.0 T magnetic resonance imaging, and cognition with a neuropsychological test battery. We used multiple regression analysis to examine proposed relationships. For analysis of AHI and brain volumes, we controlled for age, sex, education, left ventricular ejection fraction , and intracranial volume. Results: In regression models adjusting for covariates, AHI was significantly related to reduced grey matter volume in areas including the inferior temporal gyrus, fusiform gyrus, cingulate gyrus, and superior frontal gyrus (p <0.001). In white matter volume, AHI was related inversely to white matter volume in areas such as superior temporal gyrus and superior frontal gyrus (p<0.001). However, AHI was not correlated with any of the neuropsychological test scores. Conclusion: AHI was associated with reduced grey and white matter volumes in the brain. These are areas associated attention and memory. However, AHI was not related to any of the cognitive test scores. In dementia literature it has been shown that brain changes precede changes in cognition by months to years. Therefore, longitudinal, prospective studies are recommended to determine whether brain volume changes that are associated with sleep apnea precede cognitive decline in individuals with HF.