Despite being relatively rare, anti-tuberculosis drug-induced liver injury (AtDiLi) is a leading cause of acute liver failure and a major reason for treatment discontinuation, because of no specific and selective markers for AtDiLi. Herein, this study aimed to investigate whether telomere length, a biological indicator of age-related diseases, is associated with AtDiLi outcomes and could serve as an early ATDILI biomarker. Relative telomere length (RTL) in blood leukocyte of 100 age-and gendermatched healthy controls, 49 tuberculosis patients with ATDILI, and 53 tuberculosis patients with non-ATDILI was quantified using real-time polymerase chain reaction. Both tuberculosis patients with and without ATDILI had significantly shorter RTL than healthy controls. Compared with tuberculosis patients with non-ATDILI, RTL in those with ATDILI was significantly increased. Longer RTL was found to be significantly associated with increased susceptibility to ATDILI. Multivariate linear regression analysis showed that an increment in RtL was independently correlated with elevated values of aspartate aminotransferase and alanine aminotransferase assessed within 60 days after antituberculosis treatment. Kaplan-Meier curve analysis demonstrated that longer RtL was associated with elevated rates of hepatotoxicity in tuberculosis patients. Receiver-operating characteristic curve analysis unveiled a diagnostic accuracy of RtL as a novel indicator for AtDiLi progression (AUc = 0.73), which yielded more sensitive and specific values than traditional liver biomarkers including serum enzyme activities of aminotransferases measured within 7 days after treatment with anti-tuberculosis regimens. Collectively, aberrant RTL in blood leukocyte would reflect hepatotoxicity induced by antituberculosis agents and might have a potential biomarker for early AtDiLi progression.Tuberculosis is a chronic respiratory infectious disease and a leading cause of morbidity and mortality worldwide. The disease is characterized by Mycobacterium tuberculosis (MTB) infection usually affecting the lungs, leading to severe coughing, fever, and chest pains 1 that mimic features of other pathologies, thereby becoming a major public health problem. Currently, standard treatment regimens for tuberculosis patients consist of isoniazid, rifampicin, pyrazinamide, and ethambutol that shorten the treatment period and enhance the therapeutic efficacy 2 . However, these anti-tuberculosis agents have been reported to be the most important causative drug-induced liver injury (DILI) in much of developing world 3 , ultimately leading to irreversible liver failure. Despite refined usage of traditional liver biomarkers including serum enzyme activities of aminotransferases and bilirubin levels 4 , these biomarkers are inadequate for early identification of DILI, and alterations in those conventional tools are not mechanistically informative. For these reasons, it would seem more appropriate to identify and develop new more sensitive and specific DILI biomarkers, which may be he...