From Jan. 1983 to June 1984 in Yonsei University Medical College 17 patients received curative resectivesurgery due to bronchogenic carcinoma. The following results were obtained by comparing the CT findings to theoperative and histological findings of those patients. 1. The histological types of 17 cases of bronchogeniccarcinoma were squamous cell Ca. 8 cases, adenocarcinoma 7 cases, and undifferentiated Ca. 2 cases. The both ofthe undifferentiated type were confirmed by post operative histological study. 2. The lesions showing falsepositivity of mediastinal invasion are enlarged but have well circumscribed margins and separated lymph nodes. 3.In contrast, the prediction of hilar infiltration by CT gave only 25% sensitivity, 77.8% specificity and 52.9%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 andin suggesting the type of invasive staging according to the location of the lesion.