Prospective screening programs have changed the presenting clinical features of MEN 2, the association of medullary thyroid carcinoma, pheochromocytoma, and parathyroid disease. Currently, all manifestations of MEN 2 syndrome can be diagnosed at an early stage. Gene carrier status can be identified by characterization of specific mutations. Prospective screening for early medullary thyroid carcinoma by calcitonin testing and for pheochromocytoma by several techniques routinely permits identification of early manifestations.