Intravesical administration of BCG is a relatively simple procedure used successfully in the treatment of superficial transitional cell carcinoma of the urinary bladder. It is usually well tolerated with few major side effects. The authors report the case of an 80-year-old man who presented with sepsis, jaundice, hepatic and pulmonary failure 10 days after his last BCG instillation therapy, that was attributed to concurrent granulomatous hepatitis and pneumonitis due to Mycobacterium bovis dissemination. In rare instances severe life-threatening complications occur in relation with BCG instillation immunotherapy that may involve multiple organs and have different presentations and require a high index of suspicion and clinical awareness in a wide range of medical specialties.