A 76-year-old woman was admitted because of respiratory failure with bilateral multiple interstitial shadows and mediastinal adenopathy on chest CT images. Blood examination revealed eosinophilia without leukocytosis and elevated C-reactive protein levels. Corticosteroids were administered before diagnosis because of rapid respiratory failure. Although her symptoms and pulmonary lesions disappeared with steroid therapy, they recurred 4 days later. A definitive diagnosis was not obtained until bronchofiberoptic examination. At the time of recurrence 6 months later, angioimmunoblastic T-cell lymphoma (AITL) was diagnosed with axillary lymph node biopsy. AITL is rare, and shows rapid deterioration of respiratory failure with poor prognosis. Lymph node biopsy is necessary to establish a definitive diagnosis.