AbstractTwo hundred and seventy-seven patients treated by an X-ray menopause in the period 1942–52 have been followed up for an average of 16·1 years. The number of deaths from different causes were compared with the numbers reported from a similar population analysed in the mortality rates published by the Registrar-General for the Eastern Region of England and Wales. It was found that there was a significantly increased mortality from all causes in the treated group and that this was mainly attributable to an increase of deaths from cancer at heavily irradiated sites occurring more than five years after treatment. There was also a significant increase in deaths from coronary disease, myocardial degeneration and cerebrovascular disease within five years of treatment. A comparison of the incidence of cancer with the numbers to be expected calculated from the registration at the Cambridge Cancer Registration Bureau, showed a significantly increased incidence of cancer of heavily irradiated sites occurring more than five years after treatment. There was no reduction in the incidence of breast cancer, and there were no cases of leukaemia.