Book excerpt: Every year there are new and exciting developments in assisted human reproduction, but how much do we really know about the underlying causes of infertility? This volume explores recent progress in the understanding of the genetics of spermatogenesis and male infertility. Topics include fundamental advances and current problems in the development and function of the testis, an outline of clinical findings in male infertility and an overview of the role of the Y chromosome in male fertility. Comprehensive critiques of posttranscriptional control during spermatogenesis, mammalian meiotic sterility, and comparative genetics of human spermatogenesis from the perspective of yeast, Drosophila and mice provide a global overview of the field.