Background: Clinical features take important rolse in the difinitive and causative diagnosis of mediastinal tumor. Objective: Research on clinical features of mediastinal tumor in patients who were treated in the Respiratory department of Bach Mai hospital. Patients: 107 patients had a pathological diagnosis as mediastinal tumor in Respiratory department of Bach Mai hospital from April 2007 to February 2009. Method: Prospective study. Result show: 78 male and 29 female patients, mean age: 47.7 +/- 15.4 year old. The most signs and symtoms: chest pain: 57.9 percent, cough: 48.6 percent, dyspnea: 19.6 percent, hoarseness: 18.7 percent. Myasthenia was present in only 6 patients (5.6 percent). Superior vena cava was the most symtoms which was taken in clinical examination: 19.6 percent. 6.5 percent of patients without any sign and symtom. Lung cancer patients have more signs and symtoms than other thymoma (chest pain: 78.3 percent vs 54.2 percent, cough: 47.8 percent vs 20.8 percent).