Sputum induction by inhalation of hypertonic saline is a noninvasive, simple, cost effective and safe procedure to collect respiratory secre-tions from lung airways for diagnosis of various respiratory diseases. Sputum induction has higher yield in comparison to spontaneous sputum, BAL, bronchial washing and gastric lavage. It is widely used to assess airway inflammation in asthma and chronic obstructive pulmonary disease (COPD). It can be used as a complementary tool to BAL both in research and in clinical monitoring of patients with interstitial lung disease (ILD). The cells, recovered from spontaneous coughing can be used to study lung cancer, respiratory infections and in diagnosis of pneumocystis carinii pneumonia in patients infected with human immunodeficiency virus. In developing countries having high prevalence of pulmonary tuberculosis, sputum induction (SI) can increase the diagnostic yield, resulting in better categorization of patients for treatment purposes. It increases case detection rate of smear negative pulmonary tuberculosis specially in area where facili-ties for more invasive and expensive techniques are not available.