Nonspecific interstitial pneumonia (NSIP) was first described as a new category of idiopathic interstitial pneumonia in 1994. This is a disease with a more insidious onset and has a chronic course. The histological findings are unusual for other idiopathic interstitial pneumonia cases (usual interstitial pneumonia, diffuse interstitial pneumonia, and acute interstitial pneumonia). In contrast to NSIP, acute interstitial pneumonia (AIP) has an acute onset and a fulminant course with the rapid development of respiratory failure. A pathological examination demonstrated characteristic diffuse interstitial fibrosis, hyaline membranes, thrombi, and architectural derangement. Here we report a 48-year-old woman who was diagnosed pathologically NSIP, but with a rapid progressive course similar to AIP.