The important role of genetic abnormalities in the causation of human male infertility is increasingly recognized. While much remains to be learned in this fast moving field, considerable progress has been achieved over the past years both in the clinical delineation of genetic forms of male infertility and in the characterization of the responsible genes and their mutations. We review the current state of knowledge on monogenic disorders where male infertility is a major and regular feature. Clinical and molecular details are given on a total of seventeen such entities. We restrict our survey to disorders that may actually come to the clinical attention of the reproductive medicine specialist.