Blood samples were collected from 52 incident cases of histologically confirmed prostate cancer and 52 age- and town of residence-matched healthy controls in Athens, Greece. Samples were analyzed blindly in Boston, Massachusetts (USA) for testosterone (T), estradiol (E2), sex hormone-binding globulin (SHBG), and dihydrotestosterone (DHT). The data were modeled using multiple logistic regression with adjustment for age, height, body mass index (wt/ht2), years of schooling, and mutually among hormones. DHT was associated inversely, significantly, and strongly with the risk of prostate cancer, whereas T was associated marginally positively, and E2 was associated nonsignificantly inversely with the disease. No association was observed in this study with respect to SHBG.