265 hypogonadic Sardinian males, ascertained through military records of 600,000 conscripts approximately over the last thirty-seven years, were screened for their sex chromatin phenotype by buccal mucosa smears and for their karyotypes from peripheral blood lymphocyte cultures. 158 (59.4%) showed a XXY karyotype without mosaicism, 5 XX and 1 XXYY karyotypes. Seven sex chromatin negative males had Kallmann's syndrome. This report summarizes the genetic and clinical data recorded in this population sample as opposed to those reported from fertility clinics.