Viridans streptococci are still under investigation concerning epidemiology, pathogenesis and clinical presentations. We aimed to investigate the clinical presentations and outcomes of pediatric patients infected with Streptococcus mitis/oralis. Based on the accumulation of bloodstream infections (BSI) caused by S. mitis/oralis in 4 patients in our Hematology and Bone Marrow Transplantation Department at a particular time, a review of the medical and microbiological records of pediatric patients with positive blood cultures for S. mitis/oralis in the entire hospital was performed. In addition, a retrospective case-control study was conducted. Pulsed-field gel electrophoresis of S. mitisloralis in 4 patients displayed unrelatedness of the strains. A total of 53 BSI (42 BSI and 11 catheter-related BSI) were analyzed. Thirty-four percent of patients with BSI caused by S. mitis/oralis had febrile neutropenia. Clinical and microbiological outcomes were favorable and infection-related mortality was not observed. Although not significant, previous antibiotic use and trimethoprim-sulfamethoxazole prophylaxis were more common in the case group. S. mitis/oralis seems likely an important agent in bacteremic children who are particularly neutropenic because of the underlying hematologic and oncologic diseases. Prompt management of infections with appropriate antimicrobials, regarding antibiotic susceptibilities of organisms, may facilitate favorable outcomes.