Depot-medroxyprogesterone acetate (DMPA) has been used world-wide since 1964 as a contraceptive in spite of the fact that it was only in 1992 licensed for contraceptive use in the USA due to concern about a possible breast cancer risk. Two recent studies have considered DMPA use and risk of breast cancer and these and earlier studies are reviewed here. Overall, the results are reassuring but there is some evidence that breast cancer risk may be increased in women using DMPA when very young and particularly in recent users. Current knowledge of the biology of human breast cancer is such that it is difficult to judge the biological plausibility of this evidence. There is no doubt that DMPA is a highly effective form of contraception and any overall assessment must take into account all the relevant risks and benefits. Thus, the risk-benefit equations in developed and developing countries must allow for different levels of maternal mortality and morbidity, as well as differing underlying cancer rates.