SUMMARY The excretion of steroid hormone metabolites was studied in normal, thyrotoxic and myxoedematous subjects. Corticosteroid excretion was increased in thyrotoxicosis and reduced in myxoedema. In myxoedema there was also a fall of total androgen excretion due principally to a reduction of the androsterone component. There was no change in total androgen excretion in thyrotoxic subjects, but there was a fall of aetiocholanolone excretion.