Aim: To investigate direct effects of hepatitis B virus (HBV) on collagen type I in vitro. Methods: Collagen type I were measured after LX-2 cell cultured with purified or serum HBV for 12, 24 and 48 h. Furthermore, evidence of HBV infection to LX-2 were detected, and different inhibitors were used to identify pathways regulating collagen I expression. Results: The 3 x 105 IU/mL purified/serum HBV increased collagen type I mRNA expression by 2.2-/3.2- and 1.3-/1.5-fold at 24 and 48 h, respectively. Collagen type I protein in the supernatant of purified/serum HBV group also increased compared to the control group (408.0 +/- 8.0/384.4 +/- 6.8 vs 262.7 +/- 15.7 ng/mL, P < 0.05). However, the 3 x 107 IU/mL purified/serum HBV increased collagen type I expression similar to that of 3 x 105 IU/mL, while 3 x 103 IU/mL group showed no effect. Human HBV immunoglobulin alleviated HBV-induced collagen I expression, but no evidence of HBV infection was found. Neutralization of transforming growth factor beta, tumor necrosis factor alpha, platelet-derived growth factor, extracellular signal-regulated kinase and TGF-beta receptor had no obvious inhibitory effects; only inhibition of p38 mitogen-activated protein kinase decreased collagen type I mRNA expression by 0.5-/0.4- and 0.4-/0.3-fold at 24 and 48 h, respectively. It reduced collagen type I protein in the purified/serum HBV group for 48 h (252.1 +/- 14.1/251.7 +/- 18.8 vs 403.9 +/- 4.9/385.0 +/- 4.2 ng/mL, P < 0.05). Conclusion: HBV directly promotes collagen type I expression of LX-2 cells without infection in vitro.