The importance of performing anaerobic blood cultures on a routine basis has been questioned in recent reports; this prompted us to review data on episodes of anaerobic bacteremia that have occurred in our 350-bed community hospital. In 1991, 771 of 7,397 blood cultures yielded bacteria or fungi; 569 (7.7%) were true positive cultures, 35 (6.2%) of which yielded 48 anaerobic isolates from 20 patients. The charts of these patients were reviewed, and it was determined that 16 of the patients had significant anaerobic bacteremia. The outcome was fatal for seven (44%) of these 16 patients, including two who died before results were reported. The results of blood culture led to a change of antimicrobial therapy for nine (56%) of the 16 patients. The source of infection was obvious for 11 of the 16 patients, and 50% of patients were receiving antimicrobial agents active against anaerobes before culture results were obtained. Although anaerobic bacteremia is uncommon in our hospital, positive culture results often resulted in a change in antimicrobial therapy.