PURPOSE: Prostatic abscess is a very rare disease whose incidence has been reported to be approximately 0.2% in patients with urologic symptoms. Besides, it cannot be diagnosed by interview and physical examination, for which imaging studies must also be performed. In the current study, we examined the clinical usefulness of imaging studies in making a diagnosis of prostatic abscess and the effect of a fine needle aspiration based on trans-rectal ultrasonography on the treatment outcomes. MATERIALS AND METHODS: In ten patients who were diagnosed with prostatic abscess and then treated during a period ranging from January of 1995 to June of 2008 (mean age: 61.8 years, range: 40-89 years), a past history, clinical symptoms, physical examination findings, laboratory findings, trans-rectal ultrasonography findings, computed tomography findings, treatment modalities and complications were retrospectively analyzed. RESULTS: All patients complained fever and voiding dysfunction as chief complaint. On trans-rectal ultrasonography and computed tomography scans, all the ten patients had abnormal findings. In five patients, there were nonhomogenous hypo-echoic lesions on trans-rectal ultrasonography. All the patients had cystic abscess lesions detected on computed tomography scans. In four patients, in whom the diameter of lesions was greater than 1cm on computed tomography scans, a fine needle aspiration was performed on trans-rectal ultrasonography and antibiotic treatment was performed. In six patients, in whom the diameter of lesions was smaller than 1 cm on computed tomography scans, antibiotic treatment was performed. There were statistically significant differences in the length of hospital stay and the size of prostate gland between the group where a fine needle aspiration was performed using trans-rectal ultrasonography and the group where antibiotic treatment was performed (p<0.05). However, there was no significant difference in the period of antibiotic treatment (P>0.05). Length of antibiotic therapy was shorter in antibiotic therapy only group, but there was no statistically significant difference (P>0.05). CONCLUSIONS: A computed tomography is a useful diagnostic modality for prostatic abscess. Besides, a fine needle aspiration based on trans-rectal ultrasonography is one of the minimally invasive treatment regimens for prostatic abscess, whose good treatment outcomes have been well documented. Furthermore, there were no severe complications in our series.