Introduction: Tuberculosis still accounts for millions of cases of active disease and deaths worldwide. The disease mainly affects the developing countries. Modern Anti-tubercular treatment can cure virtually all patients provided correct combination treatment is taken in amount and duration. Treatment of TB has been shifted towards daily regimen with administration of daily fixed dose combination of first- line ATD as per appropriate weight bands. Objectives: 1. To observe incidence of side effects of RNTCP recommended anti TB FDCs. 2. To study compliance of patients to new Anti TB FDCs and difficulties posed by patients. Materials and Methods: A Prospective cohort study was conducted involving a total of 830 patients presenting to Department of Respiratory Medicine, Lokmanya Tilak Municipal Medical College and General Hospital, Sion, Mumbai with diagnosed tuberculosis and Registered for CAT I and CAT II anti tuberculosis therapy (ATT). Duration of study was 21 months. Follow up was done at the end of intensive phase (2 months) [at the end of maximum 3 months in extrapulmonary TB] and at the end of continuation phase (6 months for Cat I and 8 months for Cat II patients). Outcome of ATT was studied in different weight bands as per RNTCP. (Cure, Failure and treatment completed). Data was analyzed using SPSS version 22.0. Result: Among treatment categories, most patients (78.6%) were registered under Category I (new patients) as compared to retreatment cases (Category II and Category I Retreatment). Among PTB patients cure rate was 78.2%, while among extra pulmonary tuberculosis (EPTB) patients treatment completion rate was 85.2%. Compliance of patients was better with Fixed drug combination (FDCs) due to reduced pill load, single dose administration, can be conveniently given to patients of all weights as per their weight bands. Conclusion: Among adverse effects, nausea and vomiting were most common followed by joint pains. Mean compliance of patients was 84.46% in IP and 84.82 during continuation phase (CP).