Multiple endocrine neoplasia type 2 (MEN-2) is a hereditary syndrome characterized by medullary thyroid carcinoma (MTC), pheochromocytoma and hyperplasia or adenoma of the parathyroid gland with hyperparathyroidism. Recent genetic studies have identified the presence of germline missense mutations in the RET proto-oncogene in almost 100% of MEN-2 patients. We report here three generations of one MEN-2 family with rare missense mutation at codon 618 (Cys-->Arg) of the RET proto-oncogene. The first patient was surgically treated at the age of 63 years but died of bone metastasis. His two children (29-year-old daughter and 25-year-old son) were treated surgically for MTC and neck lymph node metastasis. Germline mutations of the RET proto-oncogene of these three MTC patients and two children of the 29-year-old daughter (9-year-old female and 7-year-old male) were examined. Three MTC patients and the 9-year-old female possessed the mutation. The phenotype of the family with this rare point mutation of the RET proto-oncogene is reported.