Transrectal prostatic ultrasonography is an inexpensive, non-invasive procedure which permits an accurate evaluation of the dimensions and echostructure of the prostate and seminal vesicles. Prostatic tumors may present as hypoechogenic (60-80%) or isoechogenic nodules (30%), the latter requiring the use of specific techniques, which increase the sensitivity and specificity of the procedure (contrast-enhanced color-power Doppler), to identify and characterize focal lesions. The color Doppler increases the predictive value of TRUS (62-75%) but has a low sensitivity, while the power Doppler enables us to study vessels with slow blood flow. The recent introduction of contrast medium could lead to an enhancement of the Doppler signal, thus increasing sensitivity of the exam; it is also, however, an expensive, invasive and time-consuming method. Improved test sensitivity has also increased the problems relating to the identification of very small prostatic lesions which are probably of low clinical significance.