Background: The aim of this study was to investigate the serum fibronectin (FN) levels and liver enzyme activities in patients with acute hepatitis (A, B, C) and chronic viral hepatitis (B, C); determine whether the virus types correlated with disease severity; and assess whether FN could be used as a marker of virus type or disease severity in patients. Methods: A total of 60 subjects were enrolled in the study, including 20 patients with acute hepatitis (A, B, C), 20 with chronic hepatitis (B, C), and 20 healthy controls. Serum fibronectin (FN), aspartateaminotransferase(AST),alanineaminotransferase(ALT),gamma-glutamyltranspeptidase (GGT), and albumin were measured in all patients from blood samples. Results: Serum FN levels were significantly lower in acute (122.9 µg/mL (SD 43.1), P < 0.001) and chronic hepatitis patients (135.7 µg/mL (SD 46.0), P < 0 .001) compared to controls 221.4 µg/ mL (SD 32.5). A negative correlation was found between serum FN and AST (r2 = 0.528, P < 0.001), ALT (r2 = 0.425, P < 0.001), and GGT (r2 = 0.339, P < 0.001). Additionally, high serum GGT levels (β = –0.375, P = 0.010), and low serum albumin levels (β = –0.305, P = 0.008) were associated with low serum FN levels. Conclusion: Serum FN levels were lower in both acute and chronic hepatitis patients, and an inverse relationship between serum FN and serum AST, ALT, and GGT levels was found. A decrease in serum FN levels may indicate hepatitis severity as AST and ALT represent hepatocyte damage.