Abstract: To analyze the clinical biological characteristics and prognosis of papillary thyroid microcarcinoma and to investigate the treatment and risk factors of lateral cervical lymph node metastases from papillary thyroid microcarcinoma. Methods: A total of 286 patients with papillary thyroid microcarcinoma, who were treated in Tianjin Medical University Cancer Institute and Hospital between August 2001 and August 2006, were retrospectively studied. Cases, which had lateral cervical lymph node metastases as confirmed by pathology, were chosen. Clinical data was then evaluated using SPSS17.0 statistical software package. Results: The ratio of male to female was 1:2.9, and the mean age was 45.7 years. Of the 35 patients, 18 ( 51.4% ) patients came to the hospital because of lateral cervical mass. Fourteen ( 40.0% ) patients also had Hashimoto's thyroiditis, whereas 10 ( 28.6% ) patients were extrathyroidal or had invasion into the surrounding tissue or organs. Fourteen ( 40.0% ) patients had multifocality, and carcinomas occupied the upper region of the thyroid in 55.6% patients, which were both higher than the rate in papillary thyroid microcarcinoma without lateral cervical lymph node metastases ( P < 0.05 ). Moreover, one patient also had distant metastasis. Lateral cervical lymph node metastases in compartment IV were most common, while they were rare in compartment V. There were 11 patients whose lymph nodes in compartment VI appeared negative, but their lateral cervical compartments were positive. Follow-up data were as follows: one patient relapsed into primary lateral cervical compartments; two patients had new lymph node metastases in contralateral neck; one patient had distant metastases; one patient relapsed in primary lateral cervical compartments and found new carcinoma in remnant thyroid. Conclusion: In patients with lateral cervical mass, the diagnosis of lymph node metastasis from papillary thyroid microcarcinoma should be always considered. The ratio of male to female, the mean age, and the rate of coexisting Hashimoto's thyroiditis and extrathyroidal invasion did not differ signi?cantly from papillary thyroid microcarcinoma without lateral cervical lymph node metastases. Multifocality and carcinomas occupying the upper region of the thyroid may be the risk factors of lateral cervical lymph node metastases from papillary thyroid microcarcinoma. Prognosis is relatively poor, and the disease can recur easily. Thus, positive treatment should be chosen, and long-term follow-up is necessary.