In 1975, we originally developed a mass screening program for prostatic cancer (PC) using transrectal sonography (TRS). In the primary study, males more than the age of 55 years were examined by TRS and subjects with any pathological findings on the sonogram were referred to secondary examination. In the secondary examination, biopsy of prostate was carried out under ultrasonic guidance. Since 1984, we included digital rectal examination (DRE) in the primary study. We further studied prostate specific antigen (PSA) in 1987. From 1995, mass screening program for PC using PSA has been performed. In the primary study, subjects were examined by PSA and the cut-off values were set at 4 and 10 ng/ml. Subjects whose PSA level ranged from 4.1 to 10.0 ng/ml (gray zone) were examined by DRE, TRS and PSA density (more than 0.15) in the secondary study, then the suspected subjects of PC underwent 6 sextant biopsies under interventional ultrasound. Subjects whose PSA level was more than 10.1 ng/ml were biopsied directly. According to a survey by the Foundation for prostate Research, the similar field screening has been performed in Japan by 32 groups for a total of 97,066 subjects, detecting 817 (0.8%) cancer cases up to 1995 and 431 of them (53%) were in the early stage. Prostatic screening is thus being recognized as an important part of preventive oncology at a national level in Japan.