Medullary thyroid carcinoma constitutes about 5-10% of all thyroid malignancies, but rare in children. It has frequent association with multiple endocrine neoplasia(MEN) and frequent familial occurrence. They are derived from parafollicular cells of thyroid glands and produce calcitonin. They are capable of local invasion, spread to regional lymph nodes, or distant metastases. Histopathologically, the lesions are characterized by sheets of non-follicular cells surrounded by deposits of hyaline amyloid. Aggressive surgical intervention is recommended due to the propensity of medullary thyroid carcinoma for local microvascular invasion, late recurrence and metastasis. A total thyroidectomy is generally recommended because of the high incidence of bilaterality. Recently, authors experienced a case of medullary carcinoma in child. We report this case with review of the literatures.