In the last few decades, several studies have suggested a possible association between Stressful Life Events (SLEs) and the onset of Graves' Disease (GD). However, others have criticised this association and it has not yet been possible to prove it unequivocally. At present, we are not aware of studies correlating SLE and non autoimmune thyrotoxicosis. To assess possible associations between SLEs, the onset of GD and the onset of non autoimmune thyrotoxicosis (toxic nodular goitre, TNG). A case-control retrospective study. This study included 93 subjects, divided into three groups of 31 each: GD, TNG and control (CG). The GD and TNG patients had thyroid disease diagnosed within the last 12 months, with clinical and biochemical confirmation. In the CG, psychopathological and endocrine disturbances had been ruled out. All three groups consisted of nine males (29%) and 22 females (71%). The mean age was 38.4 +/- 10.9 years in the GD group, 48.3 +/- 11.1 years in the TNG group and 41.1 +/- 11.8 years in the CG group. SLEs were evaluated (number and impact) for the 12 months preceding the onset of symptoms of thyroid disease. SLE occurrences and their impact on each group of cases were measured. To assess SLEs, we used the Life Experiences Survey (LES). Our statistical analysis included descriptive techniques and parametric and/or nonparametric comparative tests. P < 0.01 was considered statistically significant. Odds ratios were also calculated. Patients with GD had a significantly greater number of SLEs compared to the TNG group and the CG (P < 0.001). The number and impact of negative SLEs were significantly higher in GD compared to TNG and CG (P < 0.001). The difference between TNG and CG was not significant (P > 0.01). GD had a higher impact of positive SLEs than TNG (P = 0.004), and no significant differences were found between the GD group and CG. Neutral SLEs were similar in the three groups. These results suggest that SLEs are a precipitating factor of the onset of GD. We also demonstrated that SLEs do not seem to have any conclusive relationship with the onset of TNG.