In this discussion of Depo-Provera (DMPA) attention is directed to the following: pharmacology and mode of action; clinical considerations; cervical dysplasia; breast cancer; and endometrial carcinoma. DMPA, a microcrystalline suspension of medroxy-progesterone acetate, is used widely around the world as a contraceptive, particularly in developing countries. MPA (medroxy-progesterone acetate) is a synthetic progesterone which in its mycrocrystalline depot form can be delivered by simple intramuscular injection or jet injector to that depending on the dose administered plateau contraceptive blood levels will be maintained for 90-180 days when doses of 150 mg and 300 mg respectively are used. The effect of DMPA in suppressing ovulation is at the hypothalmic level where it inhibits the gonadotrophic release responsible for the midcycle surge in luteinizing hormone responsible for ovulation. When 150 mg is administered every 3 months pregnancy rates range from 0.0-1.2/100 women years. The pregnancy rates range from 0.0-3.8/100 women years when 300 mg is administered every 6 months. The drug is usually administered initially in the first 7 days of the menstrual cycle to avoid possible effects on an established pregnancy. Menstrual disturbances are the major reason for discontinuation of DMPA. The usual side effects are amenorrhea, irregular but infrequent bleeding, and a few instances of prolonged or heavy bleeding. There is no evidence to suggest that DMPA increases the risk of invasive cancer of the cervix, but the evidence regarding the incidence of cervical dysplasia is ambiguous. There have not been any cases of breast cancer that can be related to DMPA use, but DMPA toxicology studies on beagle bitches revealed an increased incidence of benign and malignant breast tumors. It is well established that in adenocarcinoma of the endometrium DMPA is effective in causing regression and preventing recurrence of this tumor.