Hilar and mediastinal lymphadenopathy may represent a diagnostic challenge in clinical practice. This article is intended to facilitate differential diagnosis by a systematic description of relevant pathologies, notably with occupational etiology. Clinical findings of relevant diseases, i. e. of tuberculosis, chronic beryllium disease, sarcoidosis, lung cancer, malignant lymphoma, Epstein-Barr virus infection, and histoplasmosis are compared.Case history, imaging and laboratory tests have important diagnostic impact. But also invasive methods can be necessary in order to exclude and prove malignancy, infection or autoimmune disease.