Two hundred and thirty-four patients who visited the urology clinic in Kitasato University Hospital were evaluated with digital rectal examination (DRE), serum prostate specific antigen (PSA) study and prostate ultrasonography. Of 71 men who underwent ultrasound-guided transrectal biopsy 19 (26.8%) were found to have prostate cancer, accounting for 8.1% (19/234) of the whole population. When PSA levels were arbitrarily divided into 0 to 2, 2.1 to 10 and greater than 10 ng/ml, the positive DRE was associated with cancer detection rate of 3.3%, 77.8% and 100%, respectively, with an overall detection rate of 32.6%. However, a normal DRE (benign-feeling gland) is associated with much less cancer detection rate of 5.9%, 28.6% and 100%, respectively, with an overall rate of only 16.0%. The positive biopsy rate was 30% (18/60) in the presence of hypoechoic lesions on sonography, but 9.1% (1/11) if absent. The positive predictive value of DRE (32.6%, 15/46) increased to 36.6% (15/41) if a hypoechoic lesion was identified sonographically and to 87.5% (14/16) if PSA levels were abnormal. One patient was found to have a microfocus of well differentiated adenocarcinoma in one of the 6 biopsy cores. Radical retropubic prostatectomy was performed in 9 of the 19 patients with clinically localized prostate cancer. On pathologic examination of the prostatectomy specimens 5 of them were upstaged to positive seminal vesicle or lymph node metastasis. The spectrum of prostate cancer detected by these modern techniques is broad and extends from tiny clinically insignificant cancer to advanced disease in its incurable stage.(ABSTRACT TRUNCATED AT 250 WORDS)