Primary mediastinal tumors, with the exception of lymphoma, are generally rare neoplasms. The diagnosis, classification, and treatment of these tumors still cause some degree of difficulty due to their low incidence and morphologic heterogeneity. This is particularly true for thymic epithelial neoplasms, that is, thymoma and thymic carcinoma, and also applies to primary neuroendocrine carcinomas of the thymus and primary mediastinal germ cell tumors. The appropriate staging of these tumors, likewise, has been a matter of debate over the years and numerous proposals for the staging of thymic epithelial neoplasms have been put forward in the last few decades. Unfortunately, variations of such proposals have been used in some instances to stage other tumors such as thymic neuroendocrine carcinomas and germ cell tumors, which has led to the often inappropriate use of a single staging system for different types of tumors with different biological behavior. This review will provide an overview of the staging of primary mediastinal tumors with special emphasis on more recent assessments in this particular area.