Contradictory findings have been reported about a possible causal relationship of life stress to Graves' disease. We evaluated this issue by investigating the occurrence of stressful life events in the year before the first signs of disease onset, using methods that have been found to be valid and reliable in psychosomatic research. Seventy consecutive patients with Graves' disease and a control group of 70 healthy subjects, matched for sociodemographic variables, were studied. Paykel's Interview for Recent Life Events (a semistructured research interview covering 64 life events) was administered to patients, not during the acute phase of illness but while on remission, by antithyroid drug treatment. Patients with Graves' disease reported significantly more life events compared to controls (p<0.001). They also had more independent events (p<0.001) and events that had an objective negative impact (p <0.001) according to an independent rater, unaware whether the events had occurred in patients or controls. All categories of events were found to be significantly more frequent in patients suffering from Graves' disease than in controls. By rigorous methods (inclusion of patients with Graves' disease only, careful dating of the onset of symptoms, accurate event definition, delay of the interview upon disease remission, use of a blind rater for judging independence and objective negative impact), our results support the concept of an excess of life events in Graves' disease. Stressful life events may affect the regulatory mechanisms of immune function in a number of ways. Within the extreme complexity of the phenomena implicated in the pathogenesis of autoimmune thyroid hyperfunction, our findings emphasize the role of emotional stress.