In this presentation a few of the ways in which genes and chromosomes influence reproductive failure have been discussed. Since the founding of The American Fertility Society 35 yr ago, genes and chromosomes have been shown to direct the control of sex determination and to play key roles in the etiology of ovarian failure and spontaneous abortions. In the future, genetic advances may be expected in other areas. The molecular basic of testicular and ovarian differentiation should become elucidated, and the knowledge clinically applicable. Increasing emphasis upon the genetic basis for preclinical embryonic losses seems likely, with unrecognized clinical losses possibly shown as an explanation for previously idiopathic infertility. Mendelian mutations will be shown responsible for some repetitive first-trimester abortions. The years 1944-1979 have seen remarkable genetic advances. By contrast, nongenetic causes have diminished in importance as factors responsible for sex determination, for ovarian failure, and for spontaneous abortion. In the next 25 yr there is every expectation that the role of genetics will further be elucidated and expanded.