The efficacy of interferon (IFN) is limited in about 1/3 of patients with chronic hepatitis B (CHB). We used two-dimensional electrophoresis (2-DE)-based proteomic strategies to identify potential serum markers predicting hepatitis B e antigen (HBeAg) seroconversion in these patients during IFN therapy. Two groups of patients were enrolled: training and validation. In the training group, 2-DE experiments and subsequent identification of altered levels of proteins showed that α-2-HS-glycoprotein, leucine-rich α-2-glycoprotein, and haptoglobin were significantly upregulated as compared with baseline levels in the HBeAg seroconversion group, whereas apolipoprotein C-III precursor, leucine-rich α-2-glycoprotein, and α-albumin were downregulated in the non-seroconversion group. For patients with HBeAg seroconversion in the training group, Western blot analyses showed that α-2-HS-glycoprotein levels in 75% of patients were significantly upregulated at the end of the treatment as compared with baseline levels. Subsequent experiments in the validation group showed that α-2-HS-glycoprotein levels were significantly increased at week 4 in 83.33% of patients in the HBeAg seroconversion group. Dynamic changes in the serum level of α-2-HS-glycoprotein may be a potential early marker for predicting HBeAg seroconversion during IFN treatment for CHB.