Excess body weight is associated with a moderately increased risk of thyroid cancer. Adipocyte-derived hormone, leptin, has been shown to enhance cell growth and migration in many cancer types. Limited evidence suggests that leptin has direct actions on the thyroid gland, but there are no data available on the effect of leptin on thyroid cancer cells. We evaluated the action of leptin on gene expression, cell growth, cell cycle, and cell migration in anaplastic (ARO), follicular (WRO) and papillary (CGTH-W3) thyroid carcinoma cell lines. Expression of long-form leptin receptors was observed in all thyroid cancer cell lines. Leptin stimulation did not alter the expression levels of leptin, leptin receptor and sodium-iodide symporter. Cell growth and cell cycle were not changed after leptin treatment. However, leptin was able to promote cell migration of papillary thyroid cancer cells, but inhibited migration of anaplastic and follicular cancer cells. In summary, our study suggests that leptin modulates cell migration of thyroid cancer cells in a cell type-specific manner.