Although the syndrome was discovered in 1903 by Erdheim and properly documented in 1954 by Wermer, it was only in the 1970s that the variety of clinical presentations was acknowledged and first attempts to codify treatments were made. Most published studies deals with selected and small size populations. Thus, many aspects of the natural history of MEN1 remains unknown as well as the optimal care of patients. In addition, although advances in genetics improved the diagnosis of MEN1, there are still clinical forms whose attachment to the syndrome is difficult: atypical, paucisymptomatic, forms the negative genetic diagnosis (10%). These clinical forms need to be clarified to ensure optimum support.