The number of elderly patients with acute decompensated heart failure (ADHF) is increasing, and it is often difficult to treat. This study aimed to evaluate the efficacy and safety of using tolvaptan early after hospitalization in elderly patients with ADHF and the prognosis one year after hospitalization. This study enrolled 185 patients with ADHF who were admitted for the first time. Tolvaptan was administered within 24 h after admission. These patients were assigned to two groups: over 80 years old (n= 109) and under 80 years old (n= 76). There were no significant differences between the two groups in the occurrence of MACCE within one year (25% vs. 20%,p= 0.59). All-cause mortality was significantly higher in the over-80 group (12% vs. 2%,p= 0.01). There were no significant differences in the incidence of worsening renal failure (11% vs. 7%,p= 0.46) and hypernatremia (5% vs. 9%,p= 1.0), and in the duration of hospitalization (19.2 days vs. 18.8 days,p= 0.8). Tolvaptan might be effective and safe in elderly patients with ADHF, and there was no difference in the incidence of MACCE within one year.