Transrectal ultrasound (TRUS) has revolutionized our ability to image the human prostate. In the present review, we have attempted to present salient observations with respect to this modality. We emphasize its use in combination with biopsy in men who are considered at risk for harboring carcinoma. The relevant English literature is reviewed. In addition, our experience with 2,231 consecutive ultrasound-guided biopsies performed at the University of Washington and the Seattle VA Medical Center is analyzed. TRUS appears to have its primary use in directing the biopsy needle into suspicious areas and in performing the so-called systematic sector approach to biopsy. The role of transrectal ultrasound in staging established malignancy or in monitoring men following therapy remains to be defined. In our experience, carcinoma was detected in 27.2% of the subjects. Carcinoma was found in 30.7% of patients with a hypoechoic sector. Of note, 18.4% of men had their only carcinoma found in isoechoic areas. Failure to biopsy isoechoic sectors would have resulted in missing almost 20% of men with carcinoma. The role of TRUS in men with initially negative biopsy is also discussed. In summary, ultrasound guided biopsy is a useful addition to our armamentarium, particularly with respect to performing biopsy. Future advances in this modality include image enhancement utilizing computer technology as well as the potential additive role of color flow ultrasound.