We have previously reported that there is a significant difference in the mean size of thyrocyte nuclei among patients with nodular goiter, follicular adenoma, and follicular carcinoma. In the present study, we have examined karyometric parameters of Hürthle cells in smears collected from 41 patients with Hürthle cells adenomas, Hürthle cells carcinomas, nodular goiter, and lymphocytic thyroiditis. The karyometric evaluation was performed with the image analysis computer system-Karyometry Manager 1.2. We measured the mean volume, the mean intersection area, and the mean perimeter of 100 nuclei in each routine smear. We found that the sizes of Hürthle cell nuclei could be arranged in the ascending order from the nodular goiter, through lymphocytic thyroiditis to Hürthle cell neoplasms, but those differences did not reach a border of statistical significance.