Abstract: Objective In order to confirm the diagnosis in clinic and have need for treatment,percutaneous needle aspiration biopsy(PNAB) was performed in anterion mediastinal tumor.This article reported the positive rate and coincidence rate of PANB of mediastinal tumor in benign and malignant pathological changes. Methods We performed PANB for anterior mediastinal tumor whose position was defined with recent chest films or CT films.If the position of anterior mediastinal tumor is near to the blood vessel,the PANB was performed under simulated location machine or CT machine guidance.The mediastinal nodules were biopsied and were used for cyto-and histopathologic examination. Results The positive rate of PANB was 70.49%.The detection rate of benign or malignant pathological changes were 38.89%,83.72%,respectively,and there was a significant differece(P＜0.01).The rates of benign or malignant tumor proved by operation were 35.29%，68.42%,respectively,and there was a significant difference(P＜0.05). Conclusion PNAB is quick and saft with high detection rate and coincidence rate for malignate pathological changes.