The RET gene is a responsible gene of multiple endocrine type 2（MEN 2）and familial medullary thyroid carcinoma（FMTC）, and the major clinical manifestation of this syndrome is a medullary thyroid carcinoma （MTC）. We have been performing RET gene diagnosis in our laboratory since 1994. Exons 10, 11, 13–16 in the RET gene have been analyzed by PCRbased DNA sequencing. Molecular diagnosis of the RET gene is indispensable in identifying MEN 2 and should be performed for all cases with MTC. However, it is difficult to maintain RET gene diagnosis for research level eternally. Therefore, RETgene diagnosis for an advanced technology to the Ministry of Health, Labour and Welfare was applied and was approved in August 2008. Until now, the RET gene diagnosis for advanced technology was done in 15 cases（11 probands and 4 relatives）. Of these, 3 probands and 4 relatives had RET gene mutation. Among them, 3 probands and 1 relative underwent total thyroidectomy after clinical screening of pheochromocytoma. We are currently accumulating the data to promote the advanced technology to the technology covered by the national health insurance.