Past and continuing studies of the influence of a prior induced abortion on subsequent perinatal complications are reviewed. Many definitive conclusions are precluded because of design problems in the extant studies and these methodological issues, therefore, form the focus for the current review. The available studies do suggest that abortion by vacuum aspiration is not a risk factor for complications of subsequent pregnancies, labor, delivery, or of newborns. Abortion by dilatation and curettage, however, may increase the risk of subsequent spontaneous abortion, low birth weight, and prematurity but these findings need to be confirmed. The impact of other abortion techniques or perinatal complications has not been studied. The more common design problems in the extant literature include: (1) failure to control for confounding maternal factors; (2) problems in reliability of reporting previous abortion; and (3) nonspecific measurement of abortion techniques. Since approximately three-quarters of all abortions performed annually in the United States are on young never-married women who may eventually wish to bear children, further rigorous research to define the risks of induced abortion is urgently required.