OBJECTIVES: To determine the frequency and pattern of cognitive dysfunction in outpatients with chronic congestive heart failure (CHF) and to identify the corresponding demographic and clinical correlates. DESIGN: Case-control study. SETTING: Outpatient clinic in a community hospital. PARTICIPANTS: Sixty-two outpatients with CHF, 53 controls diagnosed with cardiovascular disease uncomplicated by CHF (cardiac controls), and 42 healthy controls were investigated. MEASUREMENTS: Neuropsychological assessment included tests of mental speed, executive function, memory, language, and visuospatial function. Composite z-scores for five cognitive domains and mean z-score for overall cognitive performance were computed. The cutoff score to indicate cognitive impairment was defined as the overall healthy participants' cognitive z-score minus 2 standard deviations. Independent demographic and clinical predictors of cognitive impairment were identified using linear regression analysis. RESULTS: Patients with CHF showed a pattern of general cognitive impairment, including impairment of executive function, memory, language, mental speed, and attention. Twenty-five percent (P=.04) of patients with CHF were classified as cognitively impaired, compared with 15% of the cardiac controls and 4% of the healthy controls. Independent predictors of cognitive impairment in patients with CHF were estimated intelligence, New York Heart Association class, and presence of the apolipoprotein (Apo)E ε4 allele. CONCLUSION: Cognitive dysfunction is relatively common in patients with CHF, with deficits being most prominent in the domains of executive function, memory, language, and mental speed. Disease severity and ApoE genotype are likely to be important determinants for cognitive impairment in patients with chronic CHF.