Multiple endocrine neoplasia type 1 (MEN1) is a classic hereditary tumor syndrome characterized by a genetic predisposition to develop a variety of neuroendocrine neoplasias and hormone excess syndromes. The disease is caused by inactivating mutations of the MEN1 tumor suppressor gene, detectable in >95% of MEN1 families. The distinction of MEN1-associated tumors from sporadic neuroendocrine neoplasias is clinically important for providing optimal surgical and medical therapy, appropriate clinical follow-up, and counsel for affected patients and their families. Since MEN1 gene analysis became available in 1997, new diagnostic approaches have evolved in clinical management, to be reviewed in this article. Genetic screening of MEN1 families will allow definition of individual disease risk at a preclinical stage, thus helping to allocate medical resources and treatment as individually needed. These new diagnostic approaches are expected to reduce MEN1-associated morbidity and mortality, health care expenses, and psychological disease burden.