Objective To analyze CT features and related factors of mediastinal lymphoma with necrosis in order to identify other mediastinal tumor with necrosis.Methods CT features were retrospectively reviewed and related factors of necrosis were analyzed in 37 cases of mediastinal lymphoma confirmed by pathology.Results 37 cases appeared as mediastinal masses,in which 25 cases were cross-regional growth of the mediastinum,1 1 cases in anterior mediastinum and 1 case in posterior mediastinum.The largest cross-sectional area of tumors was 1.6-129.6 cm2 ,in which there were 1 case (0-10)cm2 ,8 cases (10-25)cm2 ,10 cases (25-50)cm2 ,1 5 cases(50-100)cm2 and 3 cases >100 cm2 .24 cases had necrosis ,among which 23 cases were slight enhanced and 1 case was seriously enhanced.Necrosis of mediastinal lymphoma was related to the size and CT enhancement of tumor by the logistic regression analysis(P <0.05).Conclusion Mediastinal lymphoma with necrosis is common .The necrosis of mediastinal lymphoma is related to the size and CT enhancement.Slight CT enhancement is one of differential points between mediastinal lymphoma with necrosis and other mediastinal tumor.