Multiple endocrine neoplasia(MEN) 2 syndrome is a rare familial cancer syndrome that is usually associated with cancer of the thyroid gland, adrenal gland, and parathyroid gland. Mutation in the RET protooncogene associated with the MEN 2 syndrome is seen in more than 90% of familial thyroid cancer cases. We report a female 7 years and 9 months old and a male 6 years and 8 months male pediatric patients. RET mutation was detected in both patients during family screening due to the diagnosis of MEN 2 syndrome in their families. We evaluated the patients who had no symtomps and we operated with an indication for prophylactic thyroidectomy. Transient bilateral recurrent laryngeal nerve (RLN) injury was developed in the first case, and hypocalcemia was developed in the second case. Families of patients diagnosed with MEN syndrome should be screened for RET mutation by genetic tests, and children with mutations should be scheduled for total thyroidectomy according to the risk of the mutation.