Abstract: Objective : To assess the role of video-assisted mediastinoscopy (VAM) in identifying mediastinal dis-eases. Methods : A total of 42 documented patients with undiagnosed mediastinal diseases in chest radiogra-phy (27 males, 15 females, with an average age of 52.0 years) were retrospectively analyzed. All patients un-derwent biopsy of mediastinal lesions by either cervical mediastinoscopy (n=39) or parasternal medi-astinoscopy (n=3). Results : Histological diagnosis was obtained in all patients. The diagnosis accuracy was100% (42/42). Of the 42 cases, 18 were diagnosed as malignancies and accounted for 42.9%, including 5cases of small cell lung cancer, 4 cases of squamous cell carcinoma, 3 cases of lymphoma, and 6 cases ofother types of malignant disease. Twenty-four of the 42 cases were diagnosed as benign diseases and ac-counted for 57.1%, including 17 cases of tuberculous inflammation granuloma, 4 cases of sarcoid, and 3 cas-es of other types of benign diseases. No intraoperative hemorrhage or death occurred. Conclusion : Video-as-sisted mediastinoscopy is a satisfactory method for diagnosis of mediastinal diseases with its safety, precison,and high accuracy rate.