Background Congestive heart failure is a major cause of mortality and morbidity in the elderly but the disease impact on the oldest and sickest population has not been defined. Objectives To review the mortality and hospital readmission rate of institutionalized elderly persons with congestive heart failure and to examine the relation of baseline characteristics to subsequent clinical outcomes. Methods This was a retrospective analysis based on chart review of 231 residents of the Philadelphia (Pa) Geriatric Center (63 congregate housing tenants and 168 nursing home residents) 80 years and older, hospitalized with congestive heart failure from 1989 to 1995. Patients' demographic data and clinical, electrocardiographic, and echocardiographic findings were obtained from their initial (index) hospitalization records. Subsequent outcomes were obtained from their outpatient (nursing home or office) records. Results Thirteen percent died during the index hospitalization but the total mortality during the follow-up period was 87%. One hundred forty-six patients (63%) died in the first year with a mean±SD survival of 4±4 months and a readmission rate of 3.9 per patient-year. Eighty-five patients survived the first year with a readmission rate of 1.2 per patient-year and 54 patients subsequently died, with a mean±SD survival of 28±12 months. The first-year decedents and survivors were comparable in sex, age, medical history, and electrocardiographic findings. However, patients who died in the first year, compared with survivors, were more likely to be nursing home residents (81% vs 59%), have New York Heart Association class IV heart failure (54% vs 32%), have impaired left ventricular function by echocardiogram (53% vs 32%), and have renal insufficiency (32% vs 11%). Conclusions Very elderly persons with congestive heart failure had a guarded long-term prognosis. Nursing home residency, class IV heart failure, impaired left ventricular function, and renal insufficiency were associated with higher risk for early death and repetitive hospitalizations.