A number of studies have demonstrated that high resolution computed tomography (CT) is superior to the radiography in the assessment of patients who have chronic interstitial lung disease. CT may demonstrate extensive parenchymal disease when the radiograph is normal and may allow for a confident diagnosis when the radiographic findings are nonspecific. Although well over 100 different diseases may involve the pulmonary interstitium, in practice, approximately 10 diseases account for 80% to 90% of all cases. This article reviews the CT manifestations of the most common chronic interstitial lung diseases.