256Wermer syndrome is another name for the uncommon hereditary endocrine tumor known as MEN1 (multiple endocrine neoplasia). It occurs approximately 1 in 30,000 people with an equal sex distribution experienced it. This syndrome results from mutations in tumor suppression gene/menin gene on chromosome 11. About 90% of cases have mutations inherited from afflicted parents, with secondary mutations accounting for 10% of cases. This syndrome primarily causes the neoplasm of the endocrine glands such as anterior pituitary gland (15–90% of cases), parathyroid gland (95% of cases), and the tissue of neuroendocrine tissue of gastroentero-pancreatic organ system (30–80% of cases), nonfunctional tumors are reportedly present approximately 55% of patients. The opportunity to identify MEN1-related conditions in people who do not have a hereditary MEN 1 mutation has been made possible by breakthroughs in genetic identification. Clinically significant symptoms often appear in pediatric age, and screening should begin in the second decade, however early diagnosis reduces the morbidity and mortality. The genetic basis for MEN1 means the surgery interventions like parathyroidectomy is rarely curative. This chapter gives the insight of pathophysiology of MEN1 and its diagnosis along with latest innovation in treatment and surgery intervention.