Saccharomyces cerevisiae, known as baker's yeast, is also used as a probiotic agent to treat gastroenteritis by modulating the endogenous flora and immune system. However, since there have been increasing reports of fungemia due to S.cerevisiae and its subspecies S.boulardii, it is recommended that probiotics should be cautiously used in immunosuppressed patients, people with underlying diseases and low-birth weight babies. To emphasize this phenomenon, in this report, a case of S.cerevisiae fungemia developed in a patient given probiotic treatment for antibiotic-associated diarrhea, was presented. An 88-year-old female patient was admitted to our hospital with left hip pain, hypotension, and confusion. Her medical history included hypertension, chronic renal failure, left knee replacement surgery, and recurrent urinary tract infections due to neurogenic bladder. She was transferred to the intensive care unit with the diagnosis of urosepsis. After obtaining blood and urine samples for culture, empirical meropenem (2 x 500 mg) and linezolid (1 x 600 mg) treatment were administered. A central venous catheter (CVC) was inserted and after one day of inotropic support, her hemodynamic parameters were stabilized. The urine culture obtained on admission yielded extended-spectrum beta-lactamase-producing Klebsiella pneumoniae and Escherichia coli. Urine culture was repeated after three days and no bacteria were isolated. On the 4th of admission she developed diarrhea. Toxin A/B tests for Clostridium difficile were negative. To releive diarrhea, S.boulardii (Reflor 250 mg capsules, Sanofi Aventis, Turkey) was administered twice a day, without opening capsules. Two days later, her C-reactive protein (CRP) level increased from 23.2 mg/L to 100 mg/L without fever. Her blood culture taken from the CVC yielded S.cerevisiae. Linezolid and meropenem therapies were stopped on the 13th and 14th days, respectively, while prophylactic fluconazole therapy was replaced with caspofungin 1 x 50 mg on the fifth day. After seven days of therapy CRP and serum creatinine levels decreased to 9.1 mg/L and 1.2 mg/dl, respectively; and she was discharged from the hospital with improvement. The probiotic capsules were used unopen, thus, it was proposed that S.cerevisiae fungemia originated from translocation from the intestinal mucosa. Since it was not possible to investigate the molecular genetics of the strain isolated from the blood culture and the strain present in the probiotic, a definite conclusion about the origin of the strain could not be reached. It was thought that old age and underlying disease of the patient were the related predisposing factors for S.cerevisiae fungemia. This case emphasized that clinicians should be cautious in case of probiotic application eventhough in encapsulated form, even in immunocompetent -patients with a history of long-term hospital stay and use of broad-spectrum antimicrobials since there may be a risk of S.cerevisiae fungemia development.