Purpose : To determine the CT findings of atypical carcinoid of the lung. Material and Methods : We retrospectively evaluated CT findings of six patients with atypical carcinoid that were confirmed pathologically(needle biopsy : two cases ; surgery : two cases ; surgery after needle biopsy : two cases). On CT scans, we analyzed the location, size, shape, margin, and contrast enhancement pattern of the mass, and investigated the presence of calcification, bronchial obstruction, pleural effusion, lymphadenopathy and distant metastasis. Results : In all six patients, masses were round or oval, and had a well defined lobulated margin. Two(n = 6) atypical carcinoids were central and four(n = 6) were peripheral in location. Mass size ranged from 4 to 7cm. On CECT scans, three cases were isodense, two were hypodense and one was more hyperdense than the chest wall muscle. Calcification(n = 1), bronchial obstruction(n = 1), pleural effusion(n = 2), and distant metastasis(n = 1) were also noted. Lymphadenopathy was observed in three cases(mean, two) with a size of about 1-2cm. Conclusion : The most common CT findings of an atypical carcinoid was a round or ovoid lobulated peripheral mass, with little or no lymphadenopathy. An atypical carcinoid can be misdiagnosed as small cell carcinoma, so if small cell carcinoma is the conclusion of a needle biopsy report on a mass with these CT findings, a radiologist must be aware of the possibility of atypical carcinoid.