Mediastinal teratoma is a germinal tumor that results from embryologic disorders or germ primitive cells in the mediastinum. It’s a retrospective study concerning 5 patients addressed to our center for mediastinal tumor. Main symptoms were chest pain, dyspnea and pleural effusion syndrome. Computer tomography and chest x-rays were done for 4 patients. We found a bulky mass in left pleura, an anterior and right mediastinal Cyst, an anterior and left upper mediastinal Cyst, a bulky mass anterior in the mediastinum. In one patient, echocardiography showed a pericardial effusion with compression of cardiac chambers. Surgery was cystectomy through a posterolateral thoracotomy in many cases or a median sternotomy in one case. There was any major complication. Mediastinal teratoma have to be suspected in a tumor at the chest x-rays of a young adult. Its treatment remains complete resection of the tumor by surgery to avoid a recurrence tumor