Objective To assess the results of surgical intervention on patients with medullary thyroid carcinoma(MTC), and determine the value of measuring plasma calcitonin concentration postoperatively. Methods The diagnosis and treatment of 14 patients with MTC from January 1992 to December 1998 were analysed retrospectively. Results The diagnosis of MTC in the 14 patients was confirmed by pathology. Of them, 64.3% of patients had lymph node metastases. According to AJCC staging system, 1 patient was in stage Ⅰ, 7 in stage Ⅱ, 5 in stage Ⅲ and 1 in stage Ⅳ. Of nine patients measured plasma calcitoinin after initial operation, 4 had persisted hypercalcitoninemia. In the 4 patients, MTC in residual thyroid and enarged lymph node were comfirmed by B mode ultrasounography. After re operation, the calcitonin level returned to normal in 3 cases, but one remained in higher level. Postoperative follow up ranged from 2 to 8 years, 2 patients died of the disease. Twelve patients still lived, 6 of them survived more than 5 years. Conclusions The clinical stage of MTC at the time of diagnosis is an important prognostic factor. An aggressive surgical approach at the initial operation is essential to achieve a curative effect in patient with MTC. Measuring plasma calcitonin postoperatively helps to detect residuled MTC or recurrent MTC.