BACKGROUND: Despite the widespread use of medical contraception in France, the prevalence of abortion remains stable. A cross-sectional population-based survey was designed to study the characteristics of current contraceptive use in France, the different types of contraceptive failure, and the reasons reported for not using contraception. METHODS: A representative sample of 14 704 French households was randomly selected from the telephone directory. All women who in the last 5 years had had an abortion or whose last pregnancy was unintended were selected (n = 1034), whilst a fraction (n = 1829) of the other women were randomly selected. Altogether, 2863 women answered the questionnaire. RESULTS: Only 2.7% of the women aged 18-44 years who did not wish to conceive and were sexually active did not use any contraception. However, 33% of pregnancies were estimated to be unplanned, of which 50% ended in an abortion. A total of 65% of the reported unplanned pregnancies occurred among women using contraception (21% the pill, 9% IUD, 12% condoms, 23% other method). The main reasons given for these contraceptive failures were the misuse of the methods or the failure of the partner to withdraw. Reasons for not using any contraception go beyond a simple lack of information. CONCLUSIONS: The importance of-and the reasons mentioned for-contraceptive failure show a misadaptation between women's contraceptive needs and the method they use. Improving the training of family planning providers remains a major goal to ensure that women use a contraceptive method that fits their social and sexual lifestyle.