We herein report the findings of a case of myelodysplastic syndrome that was complicated by septicemia and meningoencephalitis, both of which were caused by Bacillus cereus. In contrast to all of the previous cases of B. cereus that have been seen at our institution, this patient did not have any invasive devices, such as a central venous catheter, that could have acted as a conduit for a B. cereus infection. Although B. cereus-induced meningoencephalitis is often lethal, the immediate treatment with a regimen of antibiotics including vancomycin was effective in eradicating the infection and, therefore, in reversing both the septicemia and the meningoencephalitis.