Objective: To characterize the CT features of anterior mediastinal thymoma and lymphoma and evaluate CT findings that may help in suggesting specific diagnosis among these tumors.　　Material and Method: A total of fifty eight chest CT studies with pathological diagnosis of thymoma (n=30), and lymphoma (n =28) were retrospectively reviewed by two radiologists who were blind to the pathological results.　　The CT features such as cyst and calcification within the lesion, contrast enhancement, relation with pleura and adjacent vessels, bone invasion and lymph node enlargement were evaluated.　　Results: The presence of associated mediastinal lymphadenopathy was significantly found in lymphoma (67.9%) compared to thymoma.(P＜0.05). The presence of calcification within the lesion was significantly found in thymoma than the lymphoma (p ＜0.05). The presence of adjacent vessels relationship within the lesion was higher in lymphoma than the thymoma.(P＜0.05) The other CT findings showed no significant difference among these diseases (P＞0.05).　　Conclusion: In conclusion age, lymph nodes involvement, calcification and relationship to adjacent vessels on CT scan will be helpful to give specific diagnosis on anterior mediastinum lymphoma and thymoma.