Multiple endocrine neoplasia-1 is an autosomal dominant disorder that is characterized by the combination of tumors occurrence in the parathyroids, pancreatic, islets, and anterior pituitary. Men-1 syndrome is caused because of the mutations that occurred in MEN-1 tumor suppressor gene located on the 11q13.5 chromosome. Diagnosis for primary hyperparathyroidism, pancreatic endocrine tumors, and pituitary tumors are briefly described. This chapter also describes the treatments for primary hyperparathyroidism (PHPT), pancreatic neuroendocrine tumors (PNETs), pituitary tumors, and associated tumors like carcinoid tumors, adrenal tumors, CNS tumors, thyroid tumors, cutaneous tumors, and screening of relatives. For confirming the diagnosis of those affected and is also for identifying the relatives who are at risk of affecting with MEN-1 can be detected by using genetic testing method.