Pulmonary disease following intravesical BCG treatment. Bacillus Calmette-Guerin (BCG) is an attenuated strain of Mycobacterium bovis that has been used in the treatment of malignant disease for over 20 years and for the treatment of bladder cancer since 1976. Major complications of this treatment are infrequent. We report two cases of systemic illness with pulmonary manifestations after treatment with intravesical BCG. 