Objective To investigate the expression of interferon inducible protein-10 (IP-10) in peripheral blood mononuclear cells (PBMC) of patients with hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF), and its correlation with disease severity.Methods Eighty patients with HBV-ACLF, 60 patients with chronic hepatitis B (CHB), and 25 healthy controls were enrolled from the Affiliated Hospital of Hubei University of Arts and Science during October 2013 and February 2015.IP-10 mRNA in PBMC was measured by real time quantitative PCR.Independent sample t test was used to analyze the difference in IP-10 mRNA expression between HBV-ACLF patients with model for end-stage liver disease (MELD) ＜ 30 and ≥30, and Pearson correlation test was performed to analyze the correlations of IP-10 mRNA expression with alanine aminotransferase (ALT), total bilirubin (TBil) and international normalized ratio (INR).Results The expressions of IP-10 mRNA in HBV-ACLF patients was 1.00 ± 0.19, which was higher than those in CHB patients and healthy controls (0.64 ± 0.08 and 0.41 ± 0.06, t =3.841 and 16.661, all P ＜ 0.01).The expression of IP-10 mRNA in HBV-ACLF patients with MELD ＜ 30 was 0.96 ±0.19, which was lower than that in patients with MELD ≥ 30 (1.14 ± 0.21, t =-2.283, P ＜0.05).Pearson correlation analysis showed that IP-10 mRNA level in HBV-ACLF patients was positively correlated with ALT, TBil and INR (r =0.697, 0.738 and 0.775, all P ＜ 0.01).Conclusion IP-10 mRNA is over-expressed in PBMC of patients with HBV-ACLF, and it is correlated with disease severity, which suggests that IP-10 may play an important role in the progression of liver failure.