Patient: Male, 62-year-old Final Diagnosis: BCGitis Symptoms: Fever • general fatigue Medication: — Clinical Procedure: Bone marrow biopsy • liver biopsy Specialty: Infectious Diseases • General and Internal Medicine Objective: Rare coexistence of disease or pathology Background: Bladder cancer (BC) is the second most common cancer involving the urinary system. In non-muscle-invading BC, transurethral resection of a bladder tumor followed by intravesical immunotherapy with Bacillus Calmette-Guérin (BCG) is the usual treatment. Disseminated (or systemic) BCG infection (BCGitis) represents the most severe adverse effect of intravesical BCG therapy, presenting with high-grade fever, with or without symptoms in the urinary tract, leading to severe sepsis and death if left untreated. The treatment of choice consists of isoniazid, rifampicin, and ethambutol (with or without corticosteroids) for 6 months, and the recovery rate is extremely high. Given the fact that these drugs are hepatotoxic, treating a patient with liver cirrhosis is challenging. Case Report: We present a patient with a medical history of BC treated with transurethral resection and intravesical BCG therapy, presenting with fever, transaminasemia, and generalized weakness. Liver and bone marrow biopsies revealed liver cirrhosis and granulomas in both organs. A diagnose of BCGitis was made and the patient was treated with isoniazid, rifampicin, and ethambutol; rifampicin was substituted with moxifloxacin after 1 month due to worsening of liver laboratory results, and moxifloxacin was substituted with levofloxacin later on due to tonic-clonic seizures. The patient was treated for 4 more months with levofloxacin and for 7 more months with isoniazid and ethambutol, with no other adverse effects, preserving liver function and achieving cure of BCGitis. Conclusions: We present the case of a cirrhotic patient presenting with fever and deterioration of liver laboratory results, found to have BCGitis, and discuss possible difficulties in diagnosing and treating such patients.