The aspiration of different substances into the airways and lungs may cause a variety of pulmonary complications. These disease entities most commonly involve the posterior segment of the upper lobes and the superior segment of the lower lobes. Esophagography and computed tomography (CT) are especially useful in the evaluation of aspiration disease related to tracheoesophageal or tracheopulmonary fistula. Foreign body aspiration typically occurs in children and manifests as obstructive lobar or segmental overinflation or atelectasis. An extensive, patchy bronchopneumonic pattern may be observed in patients following massive aspiration of gastric acid or water. CT is the modality of choice in establishing the diagnosis of exogenous lipoid pneumonia, which can result from aspiration of hydrocarbons or of mineral oil or a related substance. Aspiration of infectious material manifests as necrotizing consolidation and abscess formation. The relatively low diagnostic accuracy of chest radiography in aspiration diseases can be improved with CT and by being familiar with the clinical settings in which specific complications are likely to occur. Recognition of the varied clinical and radiologic manifestations of these disease entities is imperative for prompt, accurate diagnosis, resulting in decreased morbidity and mortality rates.