BACKGROUND: To elucidate how contraceptive attitudes among Danish-born and immigrant women influence the request of induced abortion. METHODS: A case-control study, the case group comprising 1095 Danish-born women and 233 immigrant women requesting abortion, in comparison with a control group of 1295 pregnant women intending to give birth. The analysis used hospital-based questionnaire interviews. RESULTS: Lack of contraceptive knowledge and experience of contraceptive problems were associated with the choice of abortion. This association was most pronounced among immigrant women, where women lacking knowledge had a 6-fold increased odds ratio (OR) and women having experienced problems a 5-fold increased OR for requesting abortion. Further, in this group of women, a partner's negative attitude towards contraception was associated with an 8-fold increased OR for requesting abortion. Contraceptive failure was prevalent; 21% of the women who did not plan to become pregnant but intended to give birth had experienced contraceptive failure. The same applied, respectively, for 45% of the Danish-born women and 36% of immigrant women, who requested abortion. Women who had experienced contraceptive failure were significantly more likely to request abortion. CONCLUSIONS: Immigrant women seem to have more difficulties in using contraception than Danish-born women. To address this problem, there is a need for culturally sensitive information campaigns targeting this heterogonous group of women.