Mediastinal tumors have long fascinated the thoracic surgeon because of their variety and unpredictability of diagnosis prior to exploration. We report the analysis of the 110 cases of mediastinal tumors, experienced in the dept. of the thoracic and cardiovascular surgery of the National Medical Center from December 1959 to August 1983. The age distribution was relatively even and the mean age was 37 years old. The germ cell tumors were 29 cases [31%], the neurogenic tumors were 19 cases [20%], the thymomas were 16 cases [17%], the lymphomas were 8 cases [8.5%], the primary or secondary carcinomas were 11 cases [12%], the bronchogenic and the P.W cysts were 4 cases, the mesenchymal tumors were 3 cases, the TB gangliomas were 3 cases among the 94 cases, histologically analysed. The malignant tumors were 39 cases [41%]. In classified by histological types, the tumor size, location and the clinical manifestations are presented. The successful removal was done in 53 cases [96%] among 55 cases of benign mediastinal tumors. In 39 malignant cases, the surgical intervention had been done in 21 cases [54%], and inoperable cases were 16 [41%], and the operative deaths were 2 cases [5%]. [KTCS 1983;4:594-601]