While bronchoscopy is performed routinely in the clinical practice of pulmonary medicine, additional research applications have been developed using this procedure to obtain cellular and other components of the airway alveolar lining fluid from patients with a variety of lung diseases [1].The results of these studies have enhanced our understanding of the pathogenesis and management of pulmonary disease.Recently, extensive scientific data (over 200 published reports during the last five years) have accumulated, which document that investigative bronchoscopy can be safely performed to study the tracheobronchial tree of individuals with asthma and individuals with other obstructive pulmonary diseases.In subjects with asthma endoscopic procedures that include bronchoalveolar lavage [2, 3, 4], segmental airway lavage [5), mucosal biopsies, endobronchial brushing, and biopsies [6, 7, 8], placement of measurement devices [9] and direct assessment of airway physiology, can be performed when appropriate precautions are observed [10].The research potential for investigative bronchoscopy and instrumentation of the airways is considerable and it is expected that these approaches will continue to provide information about the pathogenesis of airway diseases.An earlier workshop, convened by the National Institutes of Health in 1984, developed guidelines [11] for ensuring the safety of subjects undergoing bronchoscopy and bronchoalveolar lavage.The purpose of the present workshop was to review the vast experience gained since then from the world-wide practice