Introduction <p>Although many heart failure (HF) patients have cognitive problems, little is known about the factors that influence cognitive impairment. This study was conducted to assess cognitive function and its determinants in patients with HF.</p> Methods <p>This case-control study was conducted at an outpatient cardiology clinic in Ankara. The sample consisted of 55 consecutive patients with heart failure for at least 6 months and stable for more than 1 month and 61 matched healthy individuals. Cognitive function was evaluated by Addenbrooke Cognitive Assessment Battery (ACE-R). Also, Hospital Anxiety and Depression Scale (HADS) and a patient information form to collect data for sociodemographic and clinical factors were employed.</p> Results <p>Mean age was 64.05 ± 4.24 and the time since diagnosis was 3.80 ± 1.84 years. About one-fourth (<i>n</i> = 29, 22.7%) of the patients were classified as NYHA I. This study revealed that compared to age, gender, and education-matched healthy controls, patients had worse cognitive functions in all domains of the ACE-R, especially in memory (15.06 vs. 19.47, <i>p</i> &lt; 0.001) and verbal fluency (6.38 vs. 11.07, <i>p</i> &lt; 0.001), and overall ACE-R test (75.67 vs. 88.08, <i>p</i> &lt; 0.001). Regression analysis revealed that age and waist-to-hip ratio were significant predictors of cognitive performance, while participation in social activities demonstrated a marginal trend toward significance (<i>p</i> = 0.067).</p> Conclusions <p>This study revealed that cognitive functions are impaired in patients with HF. Assessment of HF patients at outpatient clinics with short, easy-to-use cognitive tests that do not require special competence is recommended. Efforts to modify predictors of impairment could improve cognitive output among these patients.</p>