THE REPRODUCTIVE hormones - oestrogen, progesterone and testosterone - do more in the body than control reproduction. Sex hormones influence both physical and mental health and well- being, from osteoporosis and cancer to depression and premenstrual dysphoric dis- order. As the mechanisms by which these hormones exert their non-reproductive ef- fects become better known, we are beginning to under- stand how they affect health and well-being. Hormone therapies (con- traception, replacement, management of cancers, etc) are increasingly common, and can have adverse effects for women. ControlLing these requires careful manage- ment, balancing risk and benefit. An understanding of the roles and effects of the reproductive hormones allows nurses to provide best care in relation to these and to new therapies as they enter clinical practice.