Pulmonary tuberculosis produces a broad spectrum of radiographic abnormalities. During the primary phase of the disease these include pulmonary consolidation (50%), which often involves the middle or lower lobes or the anterior segment of an upper lobe; cavitation (29%) or pneumatocele formation (12%); segmental or lobar atelectasis (18%); pleural effusion (24%); hilar and mediastinal lymphadenopathy (35%); disseminated miliary disease (6%); and a normal chest radiograph (15%). During the postprimary phase of the disease, common abnormalities include exudative and/or fibroproductive parenchymal densities (100%), predominantly in the apical and posterior segments of the upper lobes (91%); cavitation (45%) with bronchogenic spread of disease (21%); marked fibrotic response in the lungs (29%); and pleural effusion, empyema, and fibrosis (18%, 4%, and 41%, respectively). Upper-lobe masslike lesions are seen occasionally (7%); spontaneous pneumothorax and intrathoracic lymphadenopathy are rare (5% each). Common causes of a missed diagnosis of tuberculosis are (1) failure to recognize hilar and mediastinal lymphadenopathy as a manifestation of primary disease in adults, (2) exclusion of tuberculosis because disease predominates in or is limited to the anterior segment of an upper lobe or the basilar segment of a lower lobe, (3) overlooking of minimal fibroproductive lesions or reporting them as inactive, (4) failure to recognize that an upper-lobe mass surrounded by satellite fibroproductive lesions might be tuberculous, and (5) failure to consider healed sequelae of primary disease or a positive purified protein derivative skin test as contributory to identifying the patient's pulmonary disease.