The initial study in the suspicion of changes in the mediastinum should always include a chest x-ray.The identification of these changes on the x-ray is a priority.Knowledge of the mediastinal references and the identification of their changes can lead to the suspicion of a disease common to each of the mediastinal spaces.When the semiology of the mediastinal lesions is taken into account, as well as its location and the three most common diseases, the possibility of making an aetiological diagnosis increases.This is a review article, using a detailed literature search, in which the radiological mediastinal references are studied, with an emphasis on the epidemiological data of each one of them.