One hundred forty-nine ultrasound (US)-guided transrectal biopsies of the prostate were performed with an 18-gauge needle mounted in a spring-loaded firing device. Two probes were used, one with its sector transducer placed at the tip of the probe and the other with its sector transducer placed at an angle of 45 degrees. All biopsies provided a diagnostic tissue core. Histologic examination of biopsy specimens showed that 78 lesions were cancerous, 17 were dysplastic, and 54 were benign. Two patients developed fever; one of these received oral antibiotics after onset of the fever. Hospitalization was not required for either patient. The authors conclude that US-guided transrectal biopsy is a safe and valuable diagnostic tool.