Leptotrichia buccalis, an anaerobic gram-negative rod, is part of the normal oral flora and has rarely been isolated from clinical material. We describe four patients with neutropenia and progressive malignancy who had symptomatic L. buccalis bacteremia, and we review an additional four cases from the literature. The mean age of the patients was 31 years (range, 7-73 years), with an equal number of males and females. The number of positive blood cultures in each case ranged from one to four (mean, two); these cultures became positive after 48-120 hours (median, 54 hours). All tested isolates were sensitive to the beta-lactam agents, clindamycin, tetracycline, and metronidazole; five of seven were sensitive to chloramphenicol; and not one was sensitive to the aminoglycosides, vancomycin, ciprofloxacin, or erythromycin. Seven patients had one or more possible portals of entry for bacteremia, including mucositis (four patients), mucositis plus esophageal lesions (two), and possible mucositis plus diverticulitis (one). L. buccalis should be considered a potential pathogen in neutropenic patients, especially when breaks in the mucosal breaks in the mucosal barriers are present.