ABSTRACTAimsMany patients develop Fontan‐associated liver disease (FALD) after undergoing the Fontan procedure—a surgical treatment for congenital heart disease such as single ventricle—owing to changes in venous pressure and cardiac output. Liver biopsy is the gold standard for diagnosing FALD, but has limitations. Magnetic resonance elastography (MRE) is a popular non‐invasive method for evaluating liver stiffness and fibrosis in FALD; however, no unified view exists. This study aimed to assess the usefulness of MRE in evaluating the pathophysiology of FALD, including its correlation with cardiovascular parameters and histological findings.Methods and ResultsThis retrospective cohort study included 22 patients with FALD who underwent MRE at Yokohama City University Hospital. Patients with other liver diseases or a history of heavy alcohol consumption were excluded. Liver biopsies were assigned a congestive hepatic fibrosis score (CHFS). Liver stiffness was measured using MRE, and hemodynamic data were obtained using cardiac catheterization. The correlation between MRE‐based liver stiffness and clinical, laboratory, and pathological findings was analyzed.Patients' median age was 21.5 years, and the Fontan procedure was performed 16.3 years (mean) ago. Biochemical findings showed elevated gamma‐glutamyl transpeptidase (GGT) levels. Mean liver stiffness measured using MRE was high (5.3 kPa), which significantly correlated with CHFS stage of liver fibrosis, and also correlated with GGT levels, fibrosis 4 index, and central venous pressure.ConclusionMRE seems a promising non‐invasive tool for liver fibrosis evaluation in FALD. However, it may also reflect hepatic congestion. Further studies are needed to establish its clinical utility and standard cutoff values.