An autopsy case of rheumatoid arthritis (RA) with acute exacerbation of interstitial pneumonia is reported. A 57-year-old woman with longstanding RA was admitted to our hospital because of progressive dyspnea. On chest roentogenogram, diffuse interstitial shadow was confirmed in both lungs. Chest computed tomography (CT) showed diffuse lesion of elevated density of CT level in both lung. She was diagnosed as an acute exacerbation of interstitial pneumonia, and treated by methylpredonisolone pulse therapy (1,000 mg/day). Although cyclosporin A (2 mg/kg/day) was combined to steroid therapy, she was died of progressive respiratory failure. The histological findings of the lung showed extensive fibrosis with alveolar damage associated with hyaline membranes, edema and hemorrhage in alveolar space.