Corelationship between thyroid function and circulating dynamics has been examined with many kinds of method. In the other hand, there has been no report about the quantitative measurement of thyroid blood flow dynamics without any surgical tecnique, but our Duplex scanning system consisting of ultrasound B-mode and pulse doppler method. In 55 cases of thyroid nodules, it was obviously showed that the superior thyroid artery flow volume increased on affected portion and much more remarkably increased in the cases of the nodules located on upper pole. In our examination, the size of nodule could be exactly related with its superior thyroid blood flow volume, which suggests that the superior thyroid blood flow has good relationship with the size and location of the nodules. However it could not be found that the relationship between the blood flow and the degree of nodules' cystic degeneration, so the study of hemodynamics in thyroid parenchyma connected with superior thyroid blood flow will be needed.