OBJECTIVE The purpose of this report is to emphasize the importance of occurrence of Streptococcus mitis meningitis in febrile neutropenic children with hematopoietic malignancy. METHODS Symptoms of meningitis and sepsis (fever, headache, changes in mental status) were seen in three patients who were severely neutropenic and undergoing cytotoxic chemotherapy for CNS relapse of their underlying malignancy (acute lymphoblastic leukemia (ALL), n = 2; Burkitt's lymphoma, n = 1). Chemotherapy had included cytosine arabinoside administered 7-14 days prior to presenting with sepsis and meningitis. All three patients had buccal mucositis or sinusitis. Blood cultures and CSF cultures showed S. mitis resistant to penicillin but sensitive to vancomycin. Vancomycin, at a dosage of 60 mg/kg/day to maximize CNS levels of antibiotic, was administered to all three children. RESULTS Two of the patients recovered from S. mitis meningitis; recovery was associated with an improvement in their peripheral granulocyte counts. One patient, who remained neutropenic, died despite being treated with both intravenous and intraventricular vancomycin. CONCLUSIONS Physicians caring for patients who are neutropenic and febrile need to be aware of the risk of meningitis occurring with S. mitis sepsis. Early treatment with high dosages of vancomycin (60 mg/kg/day) and an attempt to limit the duration of neutropenia are important factors in the outcome of such patients.