National and regional estimates of the incidence of induced abortion in Brazil, Colombia and Mexico from the late 1970s to the early 1990s indicate a clear rise in the abortion rate in Brazil and increases in the abortion ratio in all three countries. Cross-sectional analysis showed no significant correlation between the abortion rate and contraceptive use, except in Mexico in the early 1990s, where a strong positive association was observed. Longitudinally, the abortion rate increased as contraceptive use increased in most regions of Brazil and Mexico throughout the study period, and in parts of Colombia until the mid-1980s. In Colombia and the most urban region of Mexico, the abortion rate declined as contraceptive use stabilized or increased. The abortion ratio was positively associated with contraceptive use over time in nearly every region of each country. The role of abortion in fertility decline was greatest in Brazil, where the general fertility rate would have been nearly 13% higher in the early 1990s if the abortion ratio had not increased from its level in the late 1970s. Abortion tended to have a greater impact on fertility in regions where contraceptive use was low. Overall, contraceptive use appears to have been a more important determinant of fertility than abortion, but abortion has played an important subsidiary role in determining fertility levels and trends in these countries.