The American Thoracic Society-European Respiratory Society classifi-cation of idiopathic interstitial pneumonias (IIPs), published in 2002, defines the morphologic patterns on which clinical-radiologic-patho-logic diagnosis of IIPs is based. IIPs include seven entities: idiopathic pulmonary fibrosis, which is characterized by the morphologic pattern of usual interstitial pneumonia (UIP); nonspecific interstitial pneumo-nia (NSIP); cryptogenic organizing pneumonia (COP); respiratory bronchiolitis-associated interstitial lung disease (RB-ILD); desquama-tive interstitial pneumonia (DIP); lymphoid interstitial pneumonia (LIP); and acute interstitial pneumonia (AIP). The characteristic com-puted tomographic findings in UIP are predominantly basal and pe-ripheral reticular opacities with honeycombing and traction bronchiec-tasis. In NSIP, basal ground-glass opacities tend to predominate over reticular opacities, with traction bronchiectasis only in advanced dis-ease. COP is characterized by patchy peripheral or peribronchovascu-lar consolidation. RB-ILD and DIP are smoking-related diseases char-acterized by centrilobular nodules and ground-glass opacities. LIP is characterized by ground-glass opacities, often in combination with cys-tic lesions. AIP manifests as diffuse lung consolidation with ground-glass opacities, which usually progress to fibrosis in patients who sur-vive the acute phase of the disease. Correct diagnosis of IIPs can be achieved only by means of interdisciplinary consensus and stringent correlation of clinical, imaging, and pathologic findings.