Background: Lung abscess is necrosis of the pulmonary parenchyma caused by microbial infection. At present, clinical outcomes after treatment are good. However, the pulmonary parenchymal changes on the chest computed tomography (CT) after treatment are not well known. We studied the changes of pulmonary parenchyma on plane chest radiography and chest CT in patients with lung abscess following the administration of antibiotics. Methods: We retrospectively reviewed 39 patients who had lung abscess with or without combined pneumonia from January 2006 to July 2010. We studied the therapeutic response in plane chest radiography of them at 1, 2, or more than 3 months following treatment. If any chest CT of them during the study period, we reviewed. Results: Mean age of the patients was about 61.3±11.2. Mean duration of antibiotics administration was about 36.7±26.8 days. After 3 months of following plane chest radiography, 10 patients (36%) showed without residual sequelae among 28 patients. Findings from other patients showed decrease in densities (11 patients, 39%), fibrostreaky sequelae (4 patients, 14%) and bullae (3 patients, 10%). After more than 2 months, chest CT was checked only in 7 patients. Among the 7 patients, 4 patients showed no residual lesion, 3 patients showed decreased densities on plane chest radiography. Chest CT revealed fibrostreaky densities in 2 patients, ground glass opacities in 3 patients, bullous formation in 1 patient, and cystic bronchiectasis in 1 patient. Conclusion: After more than 2 months following treatment for lung abscess even though there were no lesions on plane chest radiography, chest CT showed fibrostreaky or ground glass opacity.