Transrectal ultrasonography (TRUS) images prostate cancer objectively, thus contributing much to the screening and staging of the disease and the monitoring its therapeutic effects. Further, the recent introduction of prostate specific antigen (PSA) and prostatic systematic biopsy has revolutionized the strategy for detecting prostate cancer, greatly enhancing the value of TRUS in managing prostate cancer. Prostatic volumetry and biopsy guidance are among the more highly valued and widely accepted clinical uses of TRUS. Conventional gray scale TRUS depends on the hypoechogenicity of prostate cancer, and its usefulness in diagnosing prostate cancer is considerably limited by its low sensitivity and specificity for the disease. Despite the general use of today, however, TRUS maintains its clinical utility as an imaging modality for prostate cancer and complements both the digital rectal examination (DRE) and measurement of prostate specific antigen. In urologic practice at least, TRUS should be considered indispensable, along with digital rectal examination and prostate specific antigen, for screening prostate cancer. Although color (or power) Doppler imaging, sonographic contrast agents, and three-dimensional ultrasonography have been considered as possible complements to conventional TRUS during the past decade, their clinical significance remains unconfirmed. Nonetheless, novel ultrasonic and advanced computer technologies promise to advance diagnostic approaches to prostate cancer.