We conducted a study to determine the reproductive risk in a couple who were translocation carriers. This couple, who carried balanced reciprocal translocations, experienced habitual abortions. The wife had a karyotype of 46,XX,t(7;13)(p15.3;q12.3) and the husband of 46,XY,t(1;7)(p11.1;p11.1). Chromosome study of their fourth abortus demonstrated a chimera consisting of two cell lines with a 46,XY and a 46,XX,t(1;7)(p11.1;p11.1)pat, -13, + der(7)t(7;13)(p15.3;q12.3)mat, karyotype. A review of the literature indicates that the risk of having unbalanced live offspring or of spontaneous abortion/stillborns is similar in couples in whom both were translocation carriers and in couples in whom one individual was a translocation carrier. The apparent lack of increased reproductive failure may result from the selective disadvantage of aneusomic gametes at fertilization or very early spontaneous abortions of unbalanced conceptuses.