The currently accepted empiric antibiotic therapy for bacterial infections in neutropenic patients may not cover the possibility of capnophilic and anaerobic bacteremia. Many of these infections develop in patients with severe mucositis or periodontitis, and the type of organisms recovered also suggests an oral source of infection. We present two cases of bacteremia in neutropenic patients who had been empirically treated with ceftazidime and piperacillin plus amikacin. In the first case a beta-lactamase-producing strain of Capnocytophaga ochracea was isolated; in the second case bacteremia was due to a mixture of Leptotrichia buccalis and Fusobacterium nucleatum. These observations emphasize the necessity for a reevaluation of the possible use of antimicrobial agents active against beta-lactamase-producing capnophilic organisms and anaerobic bacteria during empiric therapy in neutropenic patients with an oral source of infection.