The value of CT and sonography in the diagnosis and follow-up of abscesses of the prostate was studied in six patients with this disease. Five had CT alone, one had CT and sonography, and one had sonography only. CT findings included an enlarged gland with nonenhancing fluid-density collections that sometimes were multiseptated or had enhancing rims. Sonographic findings were similar, showing a hypoechoic mass with thick walls. Follow-up examinations after antibiotic therapy (one CT, one sonogram) showed improvement or resolution. In the patients studied, CT and sonography were useful methods to detect and follow the course of prostatic abscess.