From Jan. 1983 to June 1984 in Younsei University Medical College 17 patients received curative resective surgery dut to bronchogenic carcionma. The following results were obtained by comparing the CT findings to the operative and histological findings of those patients. 1. The histological types of 17 caes of bronchogenic carcinoma were squamous cel Ca. 8 cases, adenocarcinoma 7 cases, and undifferentiated Ca. 2 cases. The both of the undifferentiated type were confirmed by post operative histological study. 2. The lesions showing false positivity of mediastinal invasion are enlarged byt have well circumscribed margins and separated lymph modes. 3. In contrast, the prediction of hilar infiltration by CT gave only 25% sensitivity, 77.8% specificity and 52% accuracy. 4. For the clinical staging done by CT, only 47.1% were in accordance with the surgical staging. 5. However, CT is useful in selecting the patients who need invasive staging before abandoning curative resection and in suggesting the types of invasive stating accoring to the location of the lesion.