Background Despite the growing epidemic of heart failure (HF), there is limited data available to systematically compare non-cardiac comorbidities in the young-old, old-old, and oldest-old patients hospitalized for HF. The precise differences will add valuable information for better management of HF in elderly patients. Methods A total of 1053 patients aged 65 years or older hospitalized with HF were included in this study. Patients were compared among three age groups: (1) young-old: 65 to 74 years, (2) old-old: 75 to 84 years, and (3) oldest-old: >= 85 years. Clinical details of presentation, comorbidities, and prescribed medications were recorded. Results The mean age was 76.7 years and 12.7% were 85 years or older. Most elderly patients with HF (97.5%) had at least one of the non-cardiac comorbidities. The patterns of common non-cardiac comorbidities were different between the young-old and oldest-old group. The three most common non-cardiac comorbidities were anemia (53.6%), hyperlipidemia (45.9%), and diabetes (42.4%) in the young-old group, while anemia (73.1%), infection (58.2%), and chronic kidney disease (44.0%) in the oldest-old group. Polypharmacy was observed in 93.0% elderly patients with HF. Additionally, 29.2% patients were diagnosed with infection, and 67.0% patients were prescribed antibiotics. However, 60.4% patients were diagnosed with anemia with only 8.9% of them receiving iron repletion. Conclusions Non-cardiac comorbidities are nearly universal in three groups but obviously differ by age, and inappropriate medications are very common in elderly patients with HF. Further treatment strategies should be focused on providing optimal medications for age-specific non-cardiac conditions.