Thyrotropin (TSH)-producing adenoma or TSH-oma is an uncommon entity. Most cases correspond to macroadenomas, and microadenomas are exceptional. The differential diagnosis should include mainly hypophyseal resistance to thyroid hormones, which can be difficult because of normal findings of imaging studies of the pituitary gland in some cases of TSH-oma and also because of the clinical and biochemical heterogeneity of both entities. Hypophyseal surgery is the treatment of choice for TSH-omas, although clinical and biochemical recovery of hyperthyroidism is not achieved in a considerable proportion of cases. When surgery fails or is contraindicated, radiotherapy and somatostatine analogues are therapeutic alternatives. We report here two cases of TSH-producing microadenoma which were confirmed after hypophyseal surgery.