INTRODUCTION: Pulmonary TB (PTB) is one of the leading causes of death due to infectious agent above HIV/AIDS. Sputum smear microscopy is the primary diagnostic tool to detect PTB. Smear positive PTB patients have to be paid more attention as they are more likely to spread the disease in the community, as compared to patients with Extra Pulmonary Tuberculosis. Various factors which may delay the time to sputum conversion have been demonstrated, but there are very few studies which have demonstrated the impact of various ADR’s of anti–TB drugs on sputum conversion. MATERIAL AND METHOD: Open, prospective, observational, non–comparative study of 18 months duration was conducted on 100 sputum positive PTB patients of either sex, in age group of 14 to 65 years, who were on DOTS category I, and sputum conversion rate (SCR) were assessed at the end of 1st and 2nd month. RESULTS: Incidence of TB is more common in the younger age group (14–25 years) followed by elderly. Out of 100 patients, 69 became sputum negative at the end of 1st month of treatment and 81 at the end of 2nd month of treatment with Category I anti–TB drugs. SCR at end of 2 months of treatment in patients with ADR’s and without ADR’s was 79.77% and 87.5% respectively but the difference between two groups was not statistically significant (p–value: 0.474).