AIMS: Recently, liver fibrosis markers, such as the fibrosis-4 index (FIB-4), have been shown to be associated with prognosis in patients with heart failure. The fibrosis-5 (FIB-5) index, which assesses albumin, alkaline phosphatase, aspartate transaminase, alanine aminotransferase and platelet count, is a simple liver fibrosis marker that was reported to be superior to FIB-4 for differentiation of liver fibrosis. This study aimed to compare the prognostic value of FIB-4 and FIB-5 in patients with heart failure. METHODS AND RESULTS: The FIB-4 and FIB-5 scores were calculated at discharge in 906 patients hospitalized with heart failure. The patients were stratified into three groups based on their FIB-5 scores: low (n = 303), middle (n = 301), and high (n = 302) FIB-5 groups. The primary endpoint was a composite of cardiac death or rehospitalization for heart failure. The low FIB-5 group was older and had larger inferior vena cava diameters and higher brain natriuretic peptide levels than the other two groups. The primary endpoint occurred in 156 (51.5%), 110 (36.5%), and 54 patients (17.9%) in the low, middle, and high FIB-5 groups, respectively (P < 0.001). On Cox proportional hazard analysis, the low FIB-5 was independently associated with the primary endpoint after adjustment for confounding factors. The association was consistent in both patients with preserved and reduced left ventricular ejection fraction (LVEF), and there was no significant interaction between LVEF phenotypes in terms of the prognostic impact of FIB-5 (P for interaction = 0.311). FIB-5 was superior to FIB-4 as a prognostic indicator of the primary endpoint (continuous net reclassification improvement, 0.530; 95% confidence interval [CI], 0.399-0.662; P < 0.001; integrated discrimination improvement, 0.072; 95% CI, 0.057-0.088; P < 0.001). CONCLUSIONS: The FIB-5 is a useful risk stratification marker with better prognostic value than FIB-4 in patients hospitalized with heart failure.