AbstractBackgroundFrailty is an issue in patients with heart failure (HF). A Korean version of the frailty scale (K‐FRAIL) has been developed.HypothesisWe aimed to analyze the relationship between the K‐FRAIL scale and physical performance in patients with HF.MethodsThis study included 142 patients with HF aged ≥65 years from a single center. Muscular fitness was assessed using the handgrip test and knee extensor strength measurement. Aerobic capacity was assessed using the cardiopulmonary exercise test and 6‐min walk test (6MWT). Frailty was assessed using the K‐FRAIL questionnaire.ResultsPeak VO₂ and 6MWT scores significantly decreased as frailty worsened, but handgrip and knee extensor strength did not. In the multivariate analysis, peak VO₂ (β = −.31; p = .002) and 6MWT score (β = −.38; p < .001) showed significant inverse associations with the K‐FRAIL score. Based on the receiver operating characteristic curve analysis, the cut‐off values of peak VO₂ (hazard ratio, 5.08; p = .023) and 6MWT (hazard ratio, 3.99; p = .020) were independent predictors of frailty.ConclusionIn older patients with HF, physical performance correlates with the degree of frailty. The K‐FRAIL scale is correlated with the peak VO₂ and 6MWT.