MEN 1 is a rare hereditary cancer syndrome which manifests a variety of endocrine and non-endocrine neoplasms and lesions. Growing knowledge of this condition in both its molecular genetic underpinnings and its clinical implications have affected the entire spectrum of the clinical management of MEN patients. The MEN1 gene is a tumor suppressor gene, and mutations in it account for the development of the MEN1 clinical syndrome through impairment of several cell functions, such as cell proliferations, cell growth control, apoptosis, DNA replication and repair, gene expression, transcriptional machinery control, and hormone secretion. Currently, DNA testing makes possible the early identification of germline mutations in asymptomatic mutation carriers. The ever increrasing combination of genetic and clinical tools will allow early detection of MEN1-associated neoplasms, potentially improving clinical outcomes and quality of life for both affected patients and their relatives.