Objective Previous studies have described several prognostic factors for heart failure (HF); however, these results were derived from registries consisting of conventional age groups, which might not represent the increasingly aging society. The present study explored the prognostic factors for all-cause death in hospitalized patients with HF across different age categories using an acute HF registry that included relatively old patients. Methods From a total of 1,971 consecutive patients with HF, 1,136 patients were enrolled. We divided the patients into 4 groups (! 65, 66-75, 76-85, and >85 years old) to evaluate all-cause death and prognostic factors of all-cause death. Results During the mean follow-up period of 1,038 days, 445 patients (39.2%) had all-cause death. A Kaplan-Meier analysis demonstrated significantly higher incidence of all-cause death in the elderly groups than in the younger groups (log-rank p<0.001). A Cox proportional-hazard regression analysis revealed that the presence of atrial fibrillation [hazard ratio (HR): 23.3, 95% confidence interval (CI): 2.36-231.1, p=0.007] was a notable predictive factor for all-cause death in the ! 65 years old group, whereas the Clinical Frailty Scale score (HR: 1.33, 95% CI: 1.16-1.52, p<0.001) and hypoalbuminemia (HR: 0.49, 95% CI: 0.31-0.78, p= 0.003) were predictors in the >85 years old group. Conclusions Atrial fibrillation was a notable predictor of HF in young patients, whereas frailty and lowgrade albuminemia were essential predictive factors of HF in elderly patients. With the increasing number of elderly patients with HF, comprehensive multidisciplinary treatment will be necessary.