. Hepatitis C infection is a major comorbidity in patients with inherited bleeding disorders. Successful antiviral treatment leads to a reduction in liver fibrosis, as shown by liver biopsies. Liver stiffness measurement (LSM) is a non-invasive method of assessing liver fibrosis. The aim of this cohort study was to evaluate the long-term effect of successful antiviral treatment, using LSM, in HCV-infected patients with inherited bleeding disorders. The LSM were performed in 2005 (LSM 1) and 2009 (LSM 2) in 39 patients who were successfully treated for HCV. The change in liver fibrosis between LSM 1 and 2 was assessed. The median duration of HCV infection was 28.8 years. A total of 22 patients (56%) underwent successful antiviral treatment before LSM 1 (group 1), and 17 patients between LSM 1 and LSM 2 (group 2). The median time since antiviral treatment was 8.8 years in group 1 and 2.5 years in group 2. In group 1, the median results of LSM 1 and 2 were similar (6.0 vs. 5.6 kPa, P-value 0.36), so overall, patients remained stable. In three patients in this group, all treated more than 15 years ago, an increase of liver stiffness was shown. Group 2 showed a significant improvement in median LSM results (10.3 vs. 6.1 kPa, P-value <0.01), with decrease of liver stiffness in 82%. Even after a long HCV infection duration, successful antiviral treatment led to a significant improvement of fibrosis, measured by LSM, mainly in the first few years after completing treatment.