We have reported that high sodium excretion ≥ 4.0 g/day, assessed by repeated measurements of spot urine, is associated with composite cardiovascular (CV) events of heart failure (HF) hospitalization, acute coronary syndrome, cerebrovascular events, and documented CV deaths in Japanese high-risk patients with either stable and compensated congestive HF, high brain natriuretic peptide, coronary artery disease, cerebrovascular disease, chronic kidney disease, or atrial fibrillation. A total of 520 patients were enrolled. During the median follow-up period of 5.2 years, 105 (20%) experienced composite CV events, which were predominantly driven by 60 (12%) HF hospitalizations. The aim of the present study was to elucidate which subgroups of patients with high sodium excretion were associated with HF hospitalization. We divided the enrolled patients into three groups according to the amount of sodium excretion (< 3.0 g/day, 3.0–3.99 g/day (reference), and ≥ 4.0 g/day) based on a median of 14 measurements during follow-up. We assessed the hazard ratio for HF hospitalization according to age, bodyweight, and gender, using the Cox hazard model. In the total population, high sodium excretion ≥ 4.0 g/day was associated with HF hospitalization [hazard ratio (HR) 1.75, confidence interval (CI) 1.05–2.83] after adjustment for gender, age, and bodyweight, but was not associated with other CV events. In older patients (≥ 75 years old), high sodium excretion ≥ 4.0 g/day was associated with HF hospitalization after adjustment for gender and bodyweight (HR 3.25, CI 1.55–6.55), which was not observed in younger (< 75 years old) patients. In patients with lower bodyweight (< 60 kg), high sodium excretion ≥ 4.0 g/day was associated with HF hospitalization after adjustment for age and gender (HR 3.05, CI 1.34–6.61), which was not observed in heavier (≥ 60 kg) patients. High sodium excretion is associated with HF hospitalization in patients with older age and lower bodyweight in Japanese high-risk patients.