Noninvasive methods for diagnosis, assessing prognosis, and following response to treatment in idiopathic pulmonary fibrosis (IPF) have yet to prove their usefulness. We report a patient with desquamative interstitial pneumonia (DIP) in whom computed tomography (CT) suggested the diagnosis by the presence of patchy areas of haziness predominantly in a peripheral distribution. The chest x-ray and physical examinations, and the arterial blood gases showed normal findings after one month of treatment with corticosteroids, at which time the CT scan and lung volumes were still abnormal. At three months, lung volumes and the CT scan were normal. Hazy densities in a peripheral distribution on CT may indicate active IPF associated with a good prognosis.