OBJECTIVES: Our study was to assess and evaluate the effects of anti-tubercular drugs on hematological, renal and hepatic function tests in Warangal district population, Telangana state, India. METHODS: This observational prospective study was carried out in the department of respiratory medicine, Government Tuberculosis (TB) Hospital, Hanamkonda, Telangana, India. Seventy tuberculosis patients were randomly selected with normal liver and kidney function tests. Renal and liver function tests were done using spectrophotometric methods using the biosystem and flame photometer. Results obtained were collected and analyzed with the statistical package of social sciences (SPSS Version 17). Descriptive and comparative analysis was conducted. The 0.05 level of significance was used as a cut-off for statistical significance.   RESULTS: After 4 weeks of treatment, the study revealed that the characteristic renal function tests; mean plasma concentration of creatinine (mg/dL) increased from 0.77±0.18 to 2.99±1.64 and uric acid levels (mg/dL) increased from 3.05±0.86 to 4.59±0.93 showing a significant difference (p=<0.0001). The characteristic liver function tests increased significantly (p=<0.0001) with mean plasma concentration of aspartate aminotransferase (AST) (IU/L) increased from 22.47± 15.24 to 62.44±13.52 and alanine aminotransferase (ALP) (IU/L) increased from 27.05±15.28 to 64.28±15.56. Hematological Parameters also decreased significantly (p=<0.0001) with Hemoglobin (gm %) decreasing from 11.8±2.4 to 9.43±1.9 and RBC (m/cmm) decreasing from 3.8±0.9 to 3.23±0.79 in patients taking anti tubercular drugs. CONCLUSIONS: In this study, serious adverse reactions to anti-tuberculous drugs were common and resulted in changes in hematological, liver and renal function, increased hospitalization costs as well as prolongation of therapy. Drug-induced Hematological, renal and hepatic toxicities indicate adjustment of dosage and optimization of drug regimen along with proactive assessment of organ function in appropriate manner with frequent laboratory testing.