Cognitive impairment and heart failure are both serious health problems related to population ageing. Impaired cognitive function is an important but underrecognized complication of congestive heart failure (CHF). The aim of the study was to examine the sociodemographic, clinical, neuroimaging and biochemical parameters affecting cognition in CHF.Methods: Thirty-one patients with CHF (left-ventricular ejection fraction <40%) and 24 controls without CHF, all free of clinically significant cognitive impairment, participating in a case–control study were assessed using a cognitive battery (CAMCOG), a depression scale, 6-min-walk test, left-ventricular ejection fraction, semi-quantitative magnetic resonance imaging, and cortisol, aldosterone and renin concentrations.Results: The CHF patients had lower CAMCOG scores than controls (93.5 ± 6.1 vs 99.9 ± 2.4, P <0.001) and had significantly lower scores on visuospatial, executive function, visual memory and verbal learning tasks. Concentrations of renin and aldosterone were higher in patients with CHF (5.4 ± 6.0 vs 0.8 ± 0.7 mU/L, P <0.001 and 598.2 ± 306.2 vs 346.0 ± 201.5, P= 0.003). Right medial temporal lobe atrophy was more prominent in CHF (P= 0.030). Left medial temporal lobe atrophy and deep white matter hyperintensities showed moderate association with cognitive scores in CHF, whereas functional capacity and biochemical parameters were fairly correlated to cognition.Conclusion: Congestive heart failure is associated with a pattern of generalized cognitive decline. Structural brain changes, functional capacity and biochemical parameters are associated with the cognitive performance of patients with CHF, but their contribution appears modest. The design of a definitive case–control study is described.