BACKGROUNDAssessing liver fibrosis is important for predicting the efficacy of direct-acting antivirals (DAAs) and patient prognosis. Non-invasive techniques to assess liver fibrosis are becoming important. Recently, serum Mac-2 binding protein glycosylation isomer (M2BPGi) was identified as a non-invasive marker of liver fibrosis.AIMTo investigate the diagnostic accuracy of M2BPGi in assessing liver fibrosis in patients with chronic hepatitis C (CHC) treated with DAAs.METHODSFrom December 2017 to August 2018, 80 treatment-naïve adult patients with CHC who were eligible for DAAs therapy were consecutively enrolled in this observational cohort study. For 12 weeks, 65 patients were treated with sofosbuvir/daclatasvir, and 15 patients were treated with sofosbuvir/daclatasvir and a weight-based dose of ribavirin at knowledge and technology association for hepatitis C management clinic, Cairo, Egypt. We measured serum M2BPGi levels, PAPAS index, fibrosis-4 (FIB-4) score and liver stiffness measurements (LSM) at baseline and 12 weeks after the end of treatment. Serum M2BPGi levels were measured using enzyme-linked immunosorbent assay.RESULTSAll patients achieved sustained virologic response (SVR12) (100%). Serum M2BPGi levels, LSM, FIB-4 score and PAPAS index decreased significantly at SVR12 (P < 0.05). Serum M2BPGi levels correlated positively with LSM at baseline and SVR12 (P < 0.001). At baseline, compared with the FIB-4 score and PAPAS index, M2BPGi was the best marker to distinguish patients with grade F4 fibrosis (AUC = 0.801, P < 0.001), patients with grade F2 from grade F0-1 fibrosis (AUC = 0.713, P = 0.012), patients with grade F3-4 from grade F0-2 fibrosis (AUC = 0.730, P < 0.001), and patients with grade F2-4 from grade F0-1 fibrosis (AUC = 0.763, P < 0.001). At SVR12, M2BPGi had the greatest AUCs for differentiating patients with grade F4 fibrosis (AUC = 0.844, P < 0.001), patients with grade F3 from grade F0-2 fibrosis (AUC = 0.893, P = 0.002), patients with grade F3-4 from grade F0-2 fibrosis (AUC = 0.891, P < 0.001), and patients with grade F2-4 from grade F0-1 fibrosis (AUC = 0.750, P < 0.001).CONCLUSIONM2BPGi is a reliable marker for the non-invasive assessment and prediction of liver fibrosis regression in patients with CHC who achieved an SVR with DAAs therapy.