To investigate the changes and clinical significance of quantitative hepatitis B surface antigen (HBsAg) in patients with chronic hepatitis B (CHB) receiving interferon-α (IFN-α) therapy.

Total of 43 CHB patients with HBeAg-positive who received IFN-α therapy were enrolled. The levels of serum HBsAg were detected before treatment and after 1 month, 3 months and 6 months respectively; while the levels of HBV DNA, HBeAg, HBcAb and ALT were monitored, respectively.

The levels of serum HBsAg decreased during the IFN-α therpy, with significant difference (P = 0.029); the level of HBsAg at 1 month after treatment was lower than the baseline, but with no significant difference (t =-1.12, P = 0.304); the level of HBsAg at 3 and 6 months after treatment were lower than the baseline, with significant differences (t =-2.71, P = 0.015; t =-2.71, P = 0.010); there were no significant difference between other time points (P all > 0.05). After 6 months treatment, the patients with a reduction of HBsAg > 0.5 log₁₀IU/ml achieved higher ALT normalization rate (χ² =5.536, P = 0.019), HBeAg loss rate (χ² = 4.226, P = 0.040) and HBeAg seroconversion rate (χ² = 4.226, P = 0.040) than the rest patients with a reduction of HBsAg < 0.5 log₁₀IU/ml.

The levels of serum HBsAg in patients with CHB decreased during IFN-α early treatment. The patients whose serum HBsAg decreased faster had higher ALT normalization rates, HBeAg loss rates and HBeAg seroconversion rates than the other ones.