Mesenchymal stromal cells (MSCs) are potential therapy for many diseases, with the ability of tissue regeneration, repair and immunomodulation. Acute-on-chronic liver failure (ACLF) is a severe disease with high mortality. Previous studies showed that MSCs can improve the outcomes of Hepatitis B virus (HBV)-related ACLF patients. However, there are still some ACLF patients who have not benefited from MSC treatment. Thus, searching for risk factors affecting MSC efficacy in ACLF patients is of great significance for promotion of MSCs therapy. This retrospective study will perform at a single center in southern China. Consecutive HBV related-ACLF patients treated with MSCs at the Third Affiliated Hospital of Sun Yat-sen University from January 2010 to October 2018 will be included. The clinical data including survival status, liver functions, complications et al. will be collected and analyzed, with the purpose of identifying the risk factors of HBV-related ACLF patients received MSCs injection and improving the efficacy of MSCs therapy furtherly.