An 83-year-old woman with histologically confirmed Hunner's cystitis presented with persistent fever, progressive dyspnea, and pulmonary patchy infiltrates. A transbronchial biopsy specimen revealed bronchiolitis obliterans organizing pneumonia. She progressively had development of renal insufficiency, due to systemic lupus erythematosus, proved by renal biopsy specimen. She recovered under corticosteroid treatment, but irreversible renal failure made long-term hemodialysis necessary.