We measured the relative expression levels of galectin-3 mRNA to beta-actin mRNA in normal thyroid tissues, thyroid tumor tissues and thyroid-derived fibroblasts. Galectin-3 mRNA was expressed ubiquitously in both benign and malignant thyroid tumors. Although a significant increase in its expression was observed in papillary carcinomas, no significant difference was observed between follicular carcinomas and adenomas. In contrast to the previous optimistic reports using immunohistochemical analysis of the galectin-3 protein expression, these results demonstrate that galectin-3 mRNA may not be a suitable target for molecular-based diagnosis of thyroid carcinomas.