Chronic obstructive pulmonary disease (COPD) and asthma are chronic inflammatory diseases which cause considerable morbidity and mortality. A number of in vivo methods have been developed to assess airway inflammation both to study mechanistic factors leading to airway inflammation as well as to assess disease activity. These have included non-invasive tests such as pulmonary function testing, bronchial provacation testing and nuclear medicine scans. Bronchoalveolar lavage and bronchoscopic derived biopsies of the airways have provided information regarding cell populations and inflammatory mediators involved in the pathogenesis of chronic airway and lung inflammation. Induced sputum may become a less invasive means to sample the lower respiratory tract in patients with these disorders.