The application of computed tomography has advanced our ability to diagnose and treat chest infections. Although conventional computed tomography has been shown to be useful in diagnosing pulmonary disease, new technological developments including high-resolution computed tomography (HRCT) and spiral (continuous imaging) computed tomography have resulted in earlier detection and more precise characterization of parenchymal lung infections and their complications. For the immunocompetent host, computed tomographic findings are helpful in the staging of disease, in differentiating infections from tumors, and in detecting complications. For the immunocompromised host, HRCT is useful in identifying subtle infiltrates earlier than other imaging methods can. Computed tomography is also useful in guiding transthoracic biopsy, aspiration, or drainage of chest infections or abscesses. In addition, computed tomographic findings can provide guidance for surgical biopsy, bronchoscopic biopsy, and bronchoalveolar lavage.