Background: Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis, and approximately 5% of new cases are diagnosed with multidrug-resistant tuberculosis (MDR-TB). Since 2019, a shorter treatment regimen comprising 6–7 oral medications has been introduced for MDR-TB management. Although some of the newer drugs used in short regimens are associated with significant side effects, their potential nephrotoxicity has not been fully studied. Estimation of glomerular filtration rate (GFR) is a primary method for evaluating renal function. Objective: Evaluation changes in renal filtration function during the course of short and long treatment regimens for MDR-TB. Goals: To evaluate changes in GFR at different stages of treatment both regimens, and to compare the treatment outcomes between long and short regimens. Materials and Methods: A retrospective chart review was conducted among 103 patients diagnosed with MDR-TB and treated at the TB Dispensary of Bayangol District Health Center between 2017-2024. GFR was calculated using MDRD equation. Data statistically analyzed using SPSS 23.0. Results: Of the study participants, 71 (66.35%) received the long treatment regimen, while 32 (29.90%) received the short regimen. The mean age was 34.81 years for the long-regimen group and 39.59 years for the short-regimen group. In the long-regimen group, the mean eGFR (mL/ min/1.73m²) was 90.016 at the start, 75.82 at the mid-point, and 77.23 at the end of treatment. In the short-regimen group, the respective eGFR values were 68.47, 68.2, and 72.5. Additionally, 54.92% of participants in the long-regimen group received injectable treatment. Conclusion eGFR values were lower in the short treatment regimen group compared to the long regimen group. While the cure rate was higher in the short regimen group, the mortality rate was also significantly higher. Therefore, treatment success cannot be attributed solely to the type of regimen used.