AIM: Transforming growth factor (TGF)-β1, metalloproteinase(MMP)-1 and its tissue inhibitor (TIMP)-1 are consideredpredictive biomarkers of chronic hepatitis activity and fibrosis. The aim of this study was to evaluate the effect of lamivudine treatment on the plasma levels of these peptides in patients with chronic hepatitis B.METHODS: TGF-β1, MMP-1 and TIMP-1 plasma concentrations were measured with an enzyme immunoassay in 40 patients treated with lamivudine for 48 wk. Elimination of HBV-DNAand HBV antigens was evaluated 24 wk after treatment completion.RESULTS: Baseline TGF-β1 (29.6±2.2 ng/mL) and TIMP-1(1 578±93 ng/mL) significantly exceeded normal values(18.3±1.6 ng/mL and 1 102±67 ng/mL respectively). Lamivudine treatment resulted in a significant decrease of TGF-β1 andTIMP-1 during treatment with an increase after 24 wk oftreatment. Pretreatment MMP-1 levels (6.7±0.7 ng/mL) weresignificantly lower than normal values (11.9±0.9 ng/mL) and increased during treatment and follow-up. A significant correlation was noted between TGF-β1 or TIMP-1 and aminotransferases as well as fibrosis scored in liver biopsy specimens. There were no statistically significant differences of TGF-β1, TIMP-1 and MMP-1 between four groups atbaseline, 24 and 48 wk of treatment. TGF-β1 and TIMP-1 levels increased significantly in non-responders and normalized in responders at wk 72. MMP-1 also normalized in responders and decreased to values significantly lower than normal innon-responders.CONCLUSION: These findings support the role of TGF-β1,TIMP-1 and MMP-1 in the pathogenesis of chronic hepatitis B.Because of their association with hepatic injury and antiviral treatment efficacy, determination of these peptides may be useful in disease management.