OBJECTIVE: To estimate the prevalence of heart failure (HF) and left ventricular (LV) systolic dysfunction in a population-based sample of older Australians. DESIGN, SETTING AND PARTICIPANTS: A cross-sectional survey of 2000 randomly selected residents of Canberra, aged 60-86 years, conducted between February 2002 and June 2003. Participants were assessed by history, physical examination by a cardiologist, and echocardiography. MAIN OUTCOME MEASURES: Age- and sex-specific prevalence rates of clinical HF and LV systolic dysfunction (defined as LV ejection fraction < or = 50%). RESULTS: Of 1846 people eligible for our study, 1388 (75%) agreed to participate and 1275 completed all investigations (mean age, 69.4 years; 50% men). In the study sample, 72 subjects (5.6%; 95% CI, 4.4%-7.1%) had clinical HF that had been previously diagnosed and was confirmed by our assessment. A further 0.6% (95% CI, 0.3%-1.2%) had undiagnosed clinical HF (ie, evidence of structural heart disease and symptoms/signs of cardiac insufficiency without a previous diagnosis of clinical HF). Thus, the overall prevalence of clinical HF in the sample was 6.3% (95% CI, 5.0%-7.7%). Clinical HF increased in prevalence with advancing age (a 4.4-fold increase from the 60-64-years age group to the 80-86-years age group; P < 0.0001). Of the 75 subjects (5.9%; 95% CI, 4.7%-7.3%) with LV systolic dysfunction, 44 (59%) were in the preclinical stage of disease. CONCLUSION: Diagnosed HF cases represent the "tip of the iceberg" for the national burden of HF and LV systolic dysfunction. Clinically identifiable HF cases can remain undiagnosed, and the majority of people with LV systolic dysfunction are in a preclinical stage of the disease.