Whereas round pneumonia in children is well known, there are few reports of this condition in adults. Chest radiographs, CT findings, clinical manifestations, and peripheral blood results in 14 cases of round pneumonia in 14 adults were evaluated. Round pneumonias ranged in size from 1 to 7 cm. Only round pneumonia was seen in 12 cases, whereas other consolidations besides round pneumonia were present in 2 cases. Eleven of 14 cases of round pneumonia were located in the lower lobes, and 8 of these 11 cases were in the superior segment of the lower lobe. Round pneumonia showed faint density in 9 cases and clear density in 5, while the margin was slightly ill-defined in 10 and well-defined in 4. No characteristic features of round pneumonia were shown on CT scan. CT showed other consolidations besides round pneumonia in 7 of 9 cases in which CT scan was carried out. Most large-sized (more than 2 cm) round pneumonias were associated with fever and elevated WBC and CRP, whereas most small (less than 2 cm) round pneumonias were associated with normal blood results and no fever. Round pneumonia in adults is not uncommon. Most round pneumonias present as slightly dense or ill-defined masses in the posterior subpleural region of the lower lobe. Round pneumonia is suggested by a history of cough, fever, elevated WBC and CRP, and a recent chest radiograph with normal findings.