Transrectal ultrasound (TRUS) of the prostate is a specific urological examination. This morphological imaging technique is often capable of identifying the cause for raised values of prostate-specific antigen (PSA) or of clarifying hard tissue regions found during rectal palpation. Particulary in view of constantly increasing number of patients undergoing PSA tests, there is a rising need for further prostate diagnostics in otherwise asymptomatic men. Especially in the gray zone between 4 and 10 ng/ml the tissue marker PSA is frequently influenced by benign alterations, so that it is not possible--on the basis of the PSA value alone--to differentiate between benign and malignant causes. Only a clearly increased serum PSA value (>20 ng/ml) indicates the presence of a prostate carcinoma at a very high probability. However, it is necessary that all patients whose PSA is elevated, undergo a bioptical tissue sample procedure in order to try to diagnose prostate cancer. Today, we regard the technique of TRUS-based transrectal prostate biopsy, carried out with a semi-automatic coil spring device and an 18-gauge needle, as the gold standard. The core problem of visual TRUS assessment lies in its lack of specificity, especially if the examiner has only limited experience. There can be low-echo, cancer-suspicious areas that may be histologically either benign or malignant. Benign prostatic hyperplasia (BPH), vessels, centers of prostatitis as well as shadows and artefacts can often also be low in echo-density. Only adequate application of this technology and experience with this method can lead to satisfying biopsy and diagnostic results.