It has been suggested that fiberoptic bronchoscopy may induce life-threatening bronchospasm in persons with asthma. The safety of bronchoscopy and bronchoalveolar lavage (BAL) with bilateral installation of 300 ml of saline solution was assessed prospectively in ten adults with mild asthma as a part of a study of the lower respiratory tract in bronchospastic disease. Asthmatic subjects had pretreatment with intravenous aminophylline prior to bronchoscopy. Pulmonary function tests were performed prior to and immediately after the procedure, and values were compared to results in 12 normal adults undergoing bronchoscopy with BAL. One subject had mild bronchospasm (the third subject) before BAL could be performed. There were no major complications in the remaining asthmatic or normal subjects. Mean forced expiratory volume in one second (FEV1) did not change significantly in either group, and the mid-flow rate at 50 percent of vital capacity (Vmax 50%) decreased significantly only in normal subjects (p = 0.002). Moreover, none of the nine asthmatic subjects completing bronchoscopy with BAL had clinically significant bronchospasm. These results suggest that elective fiberoptic bronchoscopy and BAL can be performed safely in subjects with mild asthma.