To determine whether high-resolution CT (HRCT) is useful for diagnosing patients with multi-focal pulmonary consolidation observed on chest radiography, we reviewed the HRCT scans of 80 patients with various kinds of diseases. The patients were divided into three groups: those with infectious diseases (group A, n = 28), those with non-infectious diseases in which the use of corticosteroids was the treatment of choice (group B, n = 33), and others (group C, n = 19). Centrilobular branching structure, small nodules within the consolidation, and segmental distribution were specific or more prevalent in group A. Ground-glass attenuation, air-bronchiologram, and non-segmental distribution were more prevalent in group B. Consolidation composed of central homogeneous area and its surrounding small nodules was specific for group C, especially for sarcoidosis. In conclusion, HRCT provides more useful information in diagnosing patients with multifocal consolidation than does chest radiography or conventional CT.