OBJECTIVE To investigate cyclin D1 expression in peripheral lung cancers and its relationship with CT signs and prognosis.METHODS Cyclin D1 expression in peripheral lung cancers and its relationship with the CT imaging and prognosis were analyzed retrospectively by means of SP immunohistochemistrv and spiral CT scanning in 92 patients with peripheral lung cancer verified by pathology.RESULTS Cyclin D1 expression was related to deep lobulafion,spiculate protuberance,short thin spinules sign and mediastina lymph node metastasis.Cyclin D1 expression was not related to tumor size,cavity,pleural indentation,histological type,djfferentiation,tumor TNM stage,age or sex.Cyclin D1 was a negative prognostic factor whose over-expression indicated a poor prognosis.CONCLUSION Cyclin D1 expression may play an important role in the occurrence,progress and CT scan results of lung cancers.Cyclin D1 was a negative factor whose over-expression implied a poor prognosis.Detection of the cyclin D1 and observation of the CT scan can be considered as indexes of clinical diagnosis and prognostic evaluation.