Introduction:TSH-secreting pituitary tumors represent about 2% of all pituitary adenomas and cause central hyperthyroidism. These tumors are characterized by high levels of free thyroid hormones in the presence of nonsuppressed serum TSH concentrations.Clinical cases: 1:A 52-year womanwith menstrual irregularity and hyperprolactinemia (127ng/mL). The pituitary´s MR showed a lesion (2.0 x1.8 x1.8cm). The diagnosis of TSHoma was made later when TSH achieved 4,78µU/mL (0.27-4.2), FT4 1.9ng/dL(0.93-1.7) and TRH stimulation test compatible. Treated with Ocreotide LAR (OCT LAR) and cabergoline, but the tumor became invasive. The surgery was indicated but the patient refused. 2:A 56-year womanwith weight loss, insomnia and hair loss. TSH 5.66µU/mL(0.5-5.3), FT4 2.4ng/mL(0.7-1.6), SHBG elevated, negativeantibodies andα-GSU in the normal range. The TRH stimulation test was compatible with TSHoma. The MR presented a tumor with 0.9x0.8x0.7cm. Treated with OCT LAR: good control of hyperthyroidism symptoms. 3: A 55-year man with headachesand visual field loss. TSH 2.47µU/mL(0.5-5.3), FT4 2.3ng/mL(0.7-1.6) and negative antibodies. The pituitary MR presented a tumor with 1.1x1.0x1.0cm and compression of the optic chiasm. The diagnosis was confirmed with the TRH stimulation and high level of α-GSU. The patient had an arrhythmia and the surgery was cancelled. He has been treated successfully with OCT LAR. 4: A 45-year-old asymptomatic woman with routine tests: TSH 5.11 μUI/mL(0.27-5.0), FT4 1.97ng/dL(0.75-1.10) and negative antibodies. The diagnosis was confirmed by α-GSU, TRH stimulation andpituitary lesion with 2.1x1.9x1.8cm. She has been treated with OCTand presented normalization of hormones, α-GSU and tumorreduction. 5:A 62-year-old woman with tremors, TSH 13.9 µUI/mL (0.45-4,5), FT4 2.2 ng/mL (0.6-1.3) and positive anti-TPO. The α-GSU was normal for postmenopausal woman, but had a high α-GSU/TSH molar ratio. The pituitary´s MR showed a lesion with 5 mm. The treatment with OCT LAR was indicated. 6:A 59-year-old woman withhyperthyroidism clinic and liver cirrhosis. TSH 6.29µUI/L (0.27-4.2), FT4 3.2ng/dL(0.93-1.7),α-GSU 2251ng/L (340-4000) and a 0.9 cm pituitary lesion. There was no tumor control with OCT LAR. Transesphenoidal surgery couldn'tbe considered because of coagulation disorders. Antithyroid drugs was contraindicated due to its hepatotoxicity. Then weperformed a radiosurgery but the patient lead to death after intestinalhemorrhage. 7:A 51-year-old man complaining of palpitations, irritability and tiredness. Laboratory tests showed an increase in FT4L: 2.3ng/dL (0.9-1.7) with inappropriately normal TSH: 1.77 μUI/L (0.27-4.2) and presence of pituitary microadenoma.Conclusion: In the presence of inappropriate normal or increased TSH levels and high FT4 levels the TSH- secreting pituitary adenoma should be considered even though is a rare disease.