A family with five successive early abortions and no live births is described. The paternal grandfather and the father have a balanced reciprocal translocation, 46,XY,t(Dq–18q+). Labeling studies of the grandfather’s karyotype have revealed the translocation to involve chromosomes 13 and 18. The last three abortuses were karyotyped and had unbalanced forms of the translocation, each resulting from the segregation of an unbalanced complement: 47,XY,+13q–; 46,XX,13q–; 47,XX,t(13q–;18q+),+18. The role of reciprocal translocation in the causation of recurrent spontaneous abortions is discussed.