A case of Saccharomyces fungemia in an 8-month-old baby affected by acute myeloid leukemia while receiving intensive chemotherapy is reported. The patient was receiving prophylaxis treatment with Saccharomyces boulardii capsules (Codex) to prevent diarrhea, which is commonly associated with this type of chemotherapy. Fever spiked just the day after ending the chemotherapy course, and a strain of Saccharomyces cerevisiae was isolated from blood culture although the patient was also receiving antifungal prophylaxis with fluconazole. The patient recovered, though still neutropenic, with amphotericin-B and removal of the central venous catheter. The common biochemical characteristics make it difficult to differentiate between the strain of Saccharomyces cerevisiae and that of Saccharomyces boulardii with routine methods. In other cases, authors demonstrated an identity between the two strains with a more detailed analysis. These reports raise concern about the potential side effects of such biotherapeutic agents.