Background We examined the utility of an index of clinical exacerbations of heart failure (HF) as a surrogate measure of outcome for use in modestly sized clinical trials and observational studies. Methods Electronic records of 189 outpatients with HF in a US Veterans Affairs Medical Center were examined over a 2- to 3-year period. Data collected included patient characteristics, clinical exacerbations of HF, hospitalizations, and deaths. Subsets of patient were also assessed for HF-related level of functioning. Results Episodes of clinical exacerbation could be detected reliably (kappa = .83). An index of episodes (number of episodes divided by the time in years) was associated with lower quality of life, higher functional class, increased rate of HF hospitalization, poorer exercise tolerance, and up to 30% increased risk of mortality across 2 years. Conclusions The index of HF exacerbations is potentially a useful surrogate end point for use in clinical HF research.