The American Cancer Society National Prostate Cancer Detection Project (ACS-NPCDP) is a multidisciplinary, multicenter effort to assess the feasibility of early prostate cancer detection by digital rectal examination (DRE), transrectal ultrasound (TRUS), and prostate specific antigen (PSA) assay. By June 1990, 2425 men not previously suspected of having prostate cancer had been examined in ten participating clinical centers according to the project protocol. Three hundred ninety-six men (16.3%) were recommended for biopsy on the basis of TRUS or DRE. An analysis of the results of 330 completed biopsies showed 52 cancers detected by DRE and/or TRUS. Forty-four (84.6%) of the men with cancer had positive TRUS examination results compared with 33 (63.5%) with positive DRE. Five additional cancers were discovered as a result of elevated PSA levels. The overall detection rate was 2.4% and this rate varied by age. The detection rate in men 55 to 60 years of age was 1.3% and this rose to 3.3% in men older than 65 years of age. The estimated sensitivity was significantly greater for TRUS compared with DRE (77.2% versus 57.9%; P less than 0.05). The estimated specificity of DRE was greater than that of TRUS (96.3% versus 89.4%; P less than 0.01). The positive predictive value (PPV) for the tests varied as a function of patient and disease characteristics. The overall PPV was 28.0% for DRE and 15.2% for TRUS. The occurrence of elevated PSA levels significantly increased the PPV of both TRUS and DRE. The majority of cancers detected were at early stages. These preliminary data suggest the feasibility of using these techniques to promote cancer control, but additional data and follow-up are needed to assess the significance of the results.