Objective To evaluate the reliability and sensitivity of detection of thyroid carcinoma lymph node micrometastasis with MUC1.Methods In 488 cases of thyroid disease,1% methylene blue 1.0-2.0mL was injected into the thyroid nodule or surrounding thyroid tissue 24hours before operation.The dye-stained lymph nodes were detected at operation and RT-PCR method was used to determine MCUI in the clinically blue-stained lymph nodes.Results The detection rate of the blue-stained lymph nodes in thyroid carcinoma was 93%,and in benign lesions was 0%.In the research group,80 cases were found to have blue-stained lymph nodes,the detection rate was 95% and was higher than the pathologr diagnostic rate which was 86%(P