The role of high-resolution computed tomography in the diagnosis of interstitial lung disease is increasing as our understanding of its diagnostic accuracy improves. The characteristic findings on high-resolution computed tomography of usual interstitial pneumonia (UIP) are reticular abnormality and honeycombing with basal predominance. Honeycombing is a strong predictor of UIP and also is an important predictor of mortality. Because UIP carries the most adverse prognosis among the subtypes of idiopathic interstitial pneumonia, it is important to be able to differentiate this entity from nonspecific interstitial pneumonia and desquamative interstitial pneumonia from UIP, because these patients may show similar clinical presentations. A confident computed tomography diagnosis of UIP, in association with typical clinical features, will allow the clinician to avoid an unnecessary surgical biopsy.