Abstract: Objective : In order to offer the basis for the treatment and prognosis in patients with medullary thyroid carcinoma (MTC), the CT and calcitonin gene-related peptide (CGRP) were investi-gated. Methods : Fifty-eight cases of MTC were selected and the relationship between the CT levels and metastasis was investigated. Immunohistochemical method was used to detect the expression of CT and CGRP in 58 samples of MTC tissues. The CT and CGRP of new MTC inpatients were measured before operation and in the first few days after operation using radioimmunoassy. Results : 1) The metastatic rate of cervical lymph node had significant difference between the normal plasma CT group and elevated group (P<0.01). 2) The rate of tumoral residue had significant difference between the normal plasma CT group one month after operation and the elevated group in the same period (P<0.01). 3)In the immunohistochemical study we found that the positive rate of CT was about 98%, and the CGRP was 87.8%. 4) Part of the patients had the elevated CGRP levels, whose CT levels was normal. 5) The plasma CT levels dropped to with the stable range one week after operation. Conclusions : The CT levels are useful index to evaluate the cervical lymph node metastasis and the efficacy of surgical treatment. The plasma CGRP measurement is a way for the diagnosis of MTC especially for those patients whose preoperative CT levels are normal.