Venous blood samples were obtained from 327 unselected apparently healthy indigenous Arab men (Kuwaitis and Omanis) aged 15-79 years. Samples were also obtained from 30 Arab men with newly diagnosed prostate cancer. Serum levels of total testosterone (TT), sex hormone binding globulin (SHBG), derived free androgen index (FAI); adrenal C19 -steroids, dehydroepiandrosterone sulfate (DHEAS) and androstenedione (ADT) were determined by chemiluminescent immunoassay