Heart failure (HF)is the leading cause for 30-day all-cause readmission in older Medicare beneficiaries and 30-day all-cause readmission is associated with a higher risk of mortality. In the current analysis, we examined if that association varied by timing of 30-day all-cause readmission. Of the 8,049 Medicare beneficiaries hospitalized for HF, 1,688 had 30-day all-cause readmissions, of whom 1,519 were alive at 30 days. Of these, 626 (41%)had early (first 10 days)30-day readmission. Propensity scores for early 30-day readmission, estimated for all 1,519 patients, were used to assemble a matched cohort of 596 pairs of patients with early versus late (11 to 30 days)all-cause readmission balanced on 34 baseline characteristics. Two-year all-cause mortality occurred in 51% and 57% of matched patients with early versus late 30-day all-cause readmissions, respectively (hazard ratio [HR]associated with late 30-day readmission, 1.22; 95% confidence interval [CI], 1.04 to 1.42; p = 0.014). This association was not observed in the subset of 436 patients whose 30-day all-cause readmission was due to HF (HR, 1.01; 95% CI, 0.79 to 1.28; p = 0.963), but was observed in the subset of 756 patients whose 30-day all-cause readmission was not due to HF (HR, 1.37; 95% CI, 1.12 to 1.67; p = 0.002; p for interaction, 0.057). In conclusion, in a high-risk subset of older hospitalized HF patients readmitted within 30 days, readmission during 11 to 30 (vs 1 to 10)days was associated with a higher risk of death and this association appeared to be more pronounced in those readmitted for non–HF-related reasons.