PURPOSE: The purpose of this study was to evaluate the CT findings of peripheral small cell carninoma of the lung. MATERIALS AND METHODS: Of 45 patients with pathologically proven small cell carcinoma, with a solitary nodule in the peripheral lung distal to the segmental bronchus were included in this study. We retrospectively reviewed clinical data and CT findings including size, location, margin, enhancement pattern, lymph node enlargement, and metastasis. RESULTS: All ten masses examined had a well-defined margin, while a lobulated margin was seen in seven patients. The mean diameter was 3.8cm (2.5 -7 .0 cm), and the enhancement pattern was homogeneous in three cases and inhomogeneous in seven. Calcification or air-bronchogram was not present, and focal air density was seen in one case. In five patients, only lung mass was present, and lung mass with lymph node enlargement was seen in one patient. Distant metastasis without lymph node enlargement was noted in two patients and another two showed lymph node enlargement and distant metastasis. CONCLUSION: In ten of 45 cases of small cell carcinoma (22.2 %), the location of the nodule indicated that peripheral small cell carcinoma is not rare. The most frequent CT finding is a well-defined, lobulated mass with inhomogeneous enhancement.