Cases of thyrotoxicosis associated with a previous case of secondary hypothyroidism are extremely rare. This article presents a rare clinical case of Graves’ disease manifestation in a patient with secondary hypothyroidism after radiosurgical treatment of acromegaly. A 38-year old woman presented with acromegaly and endo-supra-laterosellar pituitary adenoma. After non-radical removal of the pituitary adenoma, radiosurgical treatment of the of the residual tissue of the pituitary tumor in the cavernous sinus area was performed. After 14 months of radiation therapy, the acromegaly was in remission; after 24 months of radiation therapy, panhypopituitarism developed (secondary hypothyroidism, adrenal insufficiency, hypogonadism, and growth hormone deficiency). Furthermore, 1.5 years after the panhypopituitarism was diagnosed, the manifestation of Graves’ disease was also noted, requiring thyrostatic and radioactive iodine treatments. Diagnostic criteria for secondary hypothyroidism are low levels of the thyroid hormones free T4 and free T3, with a reduced, normal or slightly elevated level of thyroid stimulating hormone (TSH). The criterion for the development of thyrotoxicosis in the context of the secondary hypothyroidism was the persistent increase in the level of free T4 despite adequate drug therapy with levothyroxine. In the case report, the patient’s diagnosis of Graves’ disease was confirmed by the presence of a high level of antibodies to the TSH receptor.