Intensive therapy with estrogens and androgens is employed in the palliative treatment of advanced cancer of the breast.1Since observations of the systemic effects and complications of this therapy may provide a clue to the mode of action of the sex steroids in breast cancer, they may be important. Many effects of sex hormone therapy have been recorded, but additional manifestations not commonly recognized have become prominent and more frequently noted at the higher dosages usually employed in breast cancer. The purpose of this report is to record these reactions and their relative frequency with intensive and prolonged hormone therapy. The duration of treatment varied from a few days to several years. Deleterious reactions occurred early in some patients, necessitating discontinuance of therapy. Thus, effects that might have occurred at later intervals could not be recorded. Most of the patients, however, were treated for a minimum of one month,