A 24-year-old female, in neutropenic phase after chemotherapy for acute myelogenous leukemia (on day 15) was admitted in intensive care unit for infectious pneumonia. Two strains of Stomatococcus mucilaginosus were isolated from peripheral blood cultures. No microorganisms were yielded from bronchoalveolar lavage. Patient's condition improved with prompt instigation of effective antibiotic therapy. This was the first case of septicemia and pneumonia, due to Stomatococcus mucilaginosus, in our unit. Only 26 cases occurring in neutropenic patients with underlying hematologic malignancies were reported in the literature and among these, only five cases with pneumonia were described. The complications of this normal inhabitant of the human oral cavity can be serious and fatal: septic shock, meningitis, acute respiratory distress syndrome. This study illustrate the possible virulence of Stomatococcus mucilaginosus in neutropenic patients.