Background: Heart failure (HF) and cognitive impairment are common medical conditions that are becoming increasingly prevalent in the aging Western population. They are associated with frequent hospitalisation and increased mortality, particularly when they occur simultaneously. Evidence from a number of studies suggests that HF is independently associated with impairment in various cognitive domains. Aims: This systematic literature review evaluates the relation between cognitive deterioration and heart failure. Methods: We searched electronic databases from 1966 to May 2006 for studies that investigated cognitive function in HF patients. Twenty-two controlled studies that met the inclusion criteria were selected for analysis. Study characteristics and data on global cognitive performance, memory scores, psychomotor speed and depression scores were extracted and analysed using the Cochrane Review Manager software. Results: Pooled analysis shows diminished neuropsychological performance in HF patients, as compared to control subjects. In a pooled sample of 2937 heart-failure patients and 14,848 control subjects, the odds ratio for cognitive impairment was 1.62 (95% confidence interval:1.48-1.79, p < 0.0001) among subjects with HF. Conclusion: This review confirms the relationship between HF and cognitive impairment, but it also stresses the need for additional systematic neuropsychological data and adequate neuro-imaging from representative populations of HF patients.