Background: Although the diagnostic criteria are primarily reproductive, insulin resistance is a key feature of Polycystic Ovary Syndrome (PCOS). It is known that insulin may act as a growth factor that can stimulate cell proliferation. Preliminary data hypothesized that the thyroid gland may be an additional victim of the insulin resistance syndrome, suggesting that higher levels of circulating insulin might be associated with increased thyroid volume and nodule formation. Purpose: We aimed at evaluating whether there is a difference in thyroid volume between PCOS and controls and whether there is a relationship between the degree of insulin resistance and thyroid volume in PCOS. Methods: Twenty-three PCOS, diagnosed according to the International Consensus of 2023, and forty-five healthy volunteers aged 18-40 years were enrolled. Women with history of thyroid disorders and who were taking medications that may affect insulin sensitivity or supplements containing iodine or estrogen therapy were excluded. All participants underwent a medical examination, assessment of body composition by bioimpedance and thyroid ultrasound. Fasting blood samples were collected to measure hormonal and metabolic parameters. An oral glucose tolerance test and a hyperinsulinemic euglycemic clamp were performed in PCOS women. Results: PCOS women had higher anthropometric values and blood pressure and slightly lower age; the two groups showed similar thyroid function parameters, while fasting insulinemia was higher in PCOS. 5 PCOS and 9 controls were diagnosed with thyroiditis and the analyses were stratified by thyroiditis. In the group without thyroiditis, thyroid volume was significantly higher in PCOS, while the frequency of nodules was similar between the two groups. Thyroid volume showed an association with the main anthropometric parameters, particularly with lean mass. In PCOS, no correlation between M clamp and thyroid volume was observed. Conclusion: This pilot study shows an increase in thyroid volume in PCOS women without thyroiditis, which is directly associated with lean mass. In PCOS women, thyroid volume does not seem to be related with the degree of insulin resistance.