Background: Study was done to determine incidence of ADR’s in sputum positive, pulmonary TB patients, on DOTS category I and to determine the effect of ADR’s on sputum conversion.Methods: Open, prospective, observational, non-comparative study conducted in the Department of Pharmacology in collaboration with Department of Tuberculosis and Chest Diseases, Government Medical College, Amritsar for the duration of 18 months (March 2015 to September 2016). One hundred sputum positive patients of pulmonary tuberculosis on DOTS category I, of either sex, in age group of 14 years to 65 years, were recruited and followed up during intensive phase of therapy at end of 1st and 2nd month. Causality and Severity assessment were done by using WHO-UMC causality scale and Hartwig’s severity scale respectively.Results: Out of 100 patients 84 (84%) developed one or more ADR’s and a total of 118 ADR’s occurred in our study. The most common ADR was GI upset 45(38.13%), followed by hepatitis 42 (35.59%), rash 12 (10.16%), CNS 8 (6.77%), arthritic symptoms 5 (4.23%), visual disturbance 2 (1.69%), bleeding problems 2 (1.69%), hyperuricemia 1 (0.84%) and peripheral neuropathy 1 (0.84%). Causality assessment revealed that most of ADR’s(60) were in probable category and severity assessment revealed that most of ADR’s(55) belonged to level 4 (Moderate severity). Most of the ADR’s occurred within 30 days of the start of treatment (84.74%).Conclusions: With such a high incidence of ADR’s there is a need of incorporating pharmacovigilance programme into this vital health programme for more comprehensive monitoring of tuberculosis patients on DOTS for timely prevention, detection, and management of ADR’s. This will decrease non-adherence and dropouts, and thus result in better treatment outcomes.