This prospective study was conducted to evaluate the diagnostic yield of sputum induction in patients with suspected pulmonary tuberculosis who were smear-negative on expectorated sputum initially. Five hundred and seventy five patients with evidence of cavitating lung disease on chest x-ray were included in this study. Expectorated sputum was examined for Acid Fast Bacilli (AFBs). Sputum induction was done by a transcricoid injection of 5 ml of isotonic saline (0.9% NaCl) and patients were allowed to cough vigorously and specimen collected by this method was again examined for AFBs. Maximum number of the patients was in the age range of 14-40 years. Male to female ratio was 1.5:1. Upper zone bronchiectasis was found in 310 (53.9%) patients. They were initially smear-negative. Forty six (14.8%) were found smear positive after sputum induction; 144 (25%) patients of basal bronchiectasis were smear-negative on expectorated sputum. On sputum induction, 52 (36.11%) patients were found smear-positive. Out of 94 (16.3%) patients of pneumonic consolidation, 21 (22.3%) patients were smear-positive on sputum induction and out of 27 (4.6%) cases of lung abscess, 9 (33.3%) patients were proved smear-positive on sputum induction. It was concluded that sputum induction is an effective, low cost and simple technique. It is a useful alternative to broncho-alveolar lavage, which helps the physician for improving the smear-positive case detection rate in such an area where pronchoscopy facilities are not easily available.