Saccharomyces boulardii (Ultra-Levure in France, Perenterol in the USA), is widely prescribed for treatment of diarrhoea. 1 Cases of Saccharomyces fungaemia have been reported, but the translocation of S boulardii, given orally, has seldom been suspected. Among the seven published cases of Saccharomyces fungaemia attributed to S boulardii, the responsibility of S boulardii has been shown by molecular typing in only one case. 2 Because S boulardii is similar to S cerevisiae, the usual identification tests cannot differentiate them, and both yeasts are identified as S cerevisiae.