OBJECTIVE To investigate the effects of interferon -alpha1b (IFN-alpha1b) on hepatic intercellular adhesion molecule-1 (ICAM-1) expression and serum HBV DNA in patients with chronic hepatitis B. METHODS Before and 6 months after IFN-alpha1b treatment, liver biopsy was performed in patients with chronic hepatitis B to detect the expression of ICAM-1 in the liver tissues using immunohistochemistry. Serum HBV load was detected with real-time fluorescence polymerase chain reaction. RESULT CAM-1 expression in the liver tissue was significantly down-regulated after IFN treatment in patients with severe and moderate chronic hepatitis B (P<0.05). No significant variation was noted in the expression of ICAM-1 in the livers of patients with mild chronic hepatitis B after the treatment (P>0.05). In the patients weakly positive for ICAM-1 expression (+), serum HBV DNA varied scarcely after the treatment (P>0.05), while in the patients with strong ICAM-1 positivity (++, +++, or ++++), significant variation of serum HBV DNA occurred after the treatment (P<0.05 or P<0.01). CONCLUSION The therapeutic effect of IFN-alpha1b is associated with the expression of ICAM-1 in the hepatocytes, and its expression might enhance the effects of IFN on HBV DNA in patients with chronic hepatitis B.