Anaerobic bacteria have seldom been reported in prostatic abscesses. The present study concerns four cases in which the exudate was cultured with optimal microbiological techniques. Our results showed a complex aerobic-anaerobic flora in each instance, with a total of 21 isolates, including seven aerobes and 14 anaerobes. This experience has important implications concerning culture practices and empiric antimicrobial treatment for patients with prostatic abscess.