In Mexico, recent political events have drawn increased public attention to the subject of abortion. In 2000, using a national probability sample, we surveyed 3000 Mexicans aged 15-65 about their knowledge and opinions on abortion. Forty-five per cent knew that abortion was sometimes legal in their state, and 79% felt that abortion should be legal in some circumstances. A majority of participants believed that abortion should be legal when a woman's life is at risk (82%), a woman's health is in danger (76%), pregnancy results from rape (64%) or there is a risk of fetal impairment (53%). Far fewer respondents supported legal abortion when a woman is a minor (21%), for economic reasons (17%), when a woman is single (11%) or because of contraceptive failure (11%). In spite of the influence of the Church, most Mexican Catholics believed the Church and legislators' personal religious beliefs should not factor into abortion legislation, and most supported provision of abortions in public health services in cases when abortion is legal. To improve safe, legal abortion access in Mexico, efforts should focus on increasing public knowledge of legal abortion, decreasing the Church's political influence on abortion legislation, reducing the social stigma associated with sexuality and abortion, and training health care providers to offer safe, legal abortions.