An increased incidence of Hashimoto thyroiditis has been reported in patients with Turner syndrome, but several cases of Graves' disease were also described ten to 20 years ago. We report the case of a patient with Turner syndrome who developed Graves' disease, 3 years after successful treatment with recombinant human growth hormone (GH). A diagnosis of Graves' disease was made and treatment with thiamazole was started, which resulted in normalization of the thyroid function. It is important to monitor thyroid function as well as growth parameters in patients with Turner syndrome.