A 52-year-old man who had undergone intravesical immunotherapy with BCG for transitional cell bladder carcinoma and who presented with malaise, dyspnea, non-productive cough and a reticulonodular interstitial pattern on the chest radiograph is presented. Transbronc- hial biopsy specimen revealed caseating granulomas. Although no growth was evident on tuberculosis culture of the specimens, the patient’s condition improved with antituberculous antibiotics. The mechanism for BCG-induced granulomatous inflammation is poorly understood. In our case the presence of a caseating granulomata indicates a probable infectious cause of the pulmonary disease process. An attempt to identify the organism should be made in each case of pneumonitis complicating BCG therapy and antituberculous chemotheraphy should be considered. The use of corticosteroids in such cases is still controversial and requires further investigation.