OBJECTIVE: In the acute, thyrotoxic phase, patients with Graves' disease often have both thyrotoxic and neuropsychiatric symptoms. The purpose of this prospective study was to examine health-related quality of life (HRQOL) in newly diagnosed and untreated Graves' patients and the effect of antithyroid medical treatment on HRQOL. In addition, we examined the potential influence of thyroid hormones and psychiatric symptoms on the impairment of HRQOL in the thyrotoxic phase. METHODS: A total of 30 consecutively referred patients with newly diagnosed and untreated Graves' disease and 34 age-, sex- and education-matched healthy volunteers were included in the study. HRQOL was assessed with the Medical Outcome Study 36-item Short-Form Health Status Survey (SF-36) before treatment, after reaching euthyroidism and 1 year after initiation of treatment. RESULTS: In the thyrotoxic phase of Graves' disease, HRQOL was significantly impaired, in physical, mental and social dimensions. After reaching euthyroidism, the patients reported much fewer limitations on the subscales of SF-36. One year after initiation of treatment, all SF-36 scores had normalized. However, in some patients, HRQOL continues to be impaired even 1 year after initiation of treatment, as reviewed by the individual analysis. The reduced HRQOL in the acute phase of Graves' disease was correlated to depressive and anxiety symptoms, but thyroid-associated orbitopathy also influenced HLQOL. CONCLUSIONS: Impaired HRQOL is common in the acute phase of Graves' disease. A significant proportion of the patients demonstrated persistent HRQOL impairment 1 year after initiation of treatment. Improvement of HRQOL in these patients remains a challenge for the clinician.