SummaryA systematic survey of epidemiological data concerning 160 patients suffering from thyrotoxicosis, indicates a ratio of 4.3 cases of Graves’disease (GD) against 1 case of toxic adenoma (TA). The sex ratio is not different for GD and TA cases, and clearly in favour of women (5/1), whereas age distribution is not different in men and women. GD occurs preferentially in the age group of 25 to 45 years and in the sixth decade, TA is exclusively found in patients over 35 years with an equal distribution over the fourth, fifth and sixth decade. Thyrotoxic antecedents are present in about 40% of the patients under investigation, pointing to a high recurrence rate of the disease. The incidence of thyroid disorders in the relatives of patients with TA seems not to be different from that in patients with GD.