The incidence of abortion and general characteristics of women obtaining legal abortions in the US, and the trends and effects of abortion during the 1970s are described. Statistics on the abortion ratio and abortion rate for the US by year from 1969 to 1978 are presented. Sociodemographic characteristics of women obtaining abortions (age, marital status, parity, gestational age and previous abortions) are described. The availability of abortion services and facilities and the types of procedures used and their safety are discussed. Factors which have contributed to the increasing number of legal abortions are discussed. The benefits of epidemiological data on abortion are noted.