<jats:sec id="sec001"> <jats:title>Background</jats:title> <jats:p>Limitation of instrumental activity of daily living (IADL) is independently associated with an adverse prognosis in older heart failure (HF) patients.</jats:p> </jats:sec> <jats:sec id="sec002"> <jats:title>Aims</jats:title> <jats:p>This multicenter study aims to examine the relationship between average daily rehabilitation time (ADRT) and risk of IADL decline during acute hospitalization in older patients with HF.</jats:p> </jats:sec> <jats:sec id="sec003"> <jats:title>Methods</jats:title> <jats:p>Four hundred eleven older patients who were hospitalized due to acute HF and underwent rehabilitation were divided into three groups based on the tertile of the ADRT: short, intermediate, and long groups. IADL was assessed by the National Center for Geriatrics and Gerontology Activities of Daily Living (NCGG-ADL) scale. Change in NCGG-ADL (Δ NCGG-ADL) was calculated by subtracting the pre-hospitalization score from the at-discharge score and IADL decline was defined as Δ NCGG-ADL < = −1 point. Logistic regression analysis was carried out examining the association between ADRT and occurrence of IADL decline.</jats:p> </jats:sec> <jats:sec id="sec004"> <jats:title>Results</jats:title> <jats:p>The ADRT was 23.9, 32.0, and 38.6 minutes in short, intermediate, and long group, respectively. The proportion of patients with IADL decline during hospitalization was 21% among all subjects and short group had the highest proportion of IADL decline (33%) and long group had the lowest proportion (14%). The long group had significantly lower odds of IADL decline compared with the short group (OR:0.475, 95% CI:0.231–0.975, P = 0.042). Among the items of NCGG-ADL scale, significant decreases in the “go out by oneself”, “travel using a bus or train”, “shop for necessities”, “vacuum”, and “manage medication” were observed at discharge compared to pre-hospitalization in the short group (p<0.01, p<0.01, p<0.01, p<0.05, and p<0.05).</jats:p> </jats:sec> <jats:sec id="sec005"> <jats:title>Conclusions</jats:title> <jats:p>The present study demonstrated that short of ADRT may be associated with the risk of IADL decline during hospitalization in older patients with HF.</jats:p> </jats:sec>