Zearalenone (ZEA) and its derivatives are mycotoxins with estrogenic effects on mammals. The biotransformation for ZEA in animals involves the formation of two major metabolites, - and -zearalenol (-ZOL and -ZOL), which are subsequently conjugated with glucuronic acid. The capability of Saccharomyces cerevisiae strains isolated from silage to eliminate ZEA and its derivatives -ZOL and -ZOL was investigated as, also, the mechanisms involved. Strains were grown on Yeast Extract-Peptone-Dextrose medium supplemented with the mycotoxins and their elimination from medium was quantified over time by HPLC-FL. A significant effect on the concentration of ZEA was observed, as all the tested strains were able to eliminate more than 90% of the mycotoxin from the culture medium in two days. The observed elimination was mainly due to ZEA biotransformation into -ZOL (53%) and -ZOL (8%) rather than to its adsorption to yeast cells walls. Further, the biotransformation of -ZOL was not observed but a small amount of -ZOL (6%) disappeared from culture medium. ZEA biotransformation by yeasts may not be regarded as a full detoxification process because both main end-products are still estrogenic. Nonetheless, it was observed that the biotransformation favors the formation of -ZOL which is less estrogenic than ZEA and -ZOL. This metabolic effect is only possible if active strains are used as feed additives and may play a role in the detoxification performance of products with viable S. cerevisiae cells. ; Grants from CYTED, CNPq, CAPES-DS, and FAPUR/UFRRJ (Brazil). This work was also funded by FEDER funds through the “Programa Operacional Factores de Competitividade-COMPETE” and by national funds through “Fundação para a Ciência e a Tecnologia -FCT”, Ref. FCOMP-01-0124-F EDER-028029 and PTDC/AGR-TEC/3900/2012,respectively. FCT Strategic Project PEst-OE/EQB/LA0023/2013 and the Project “BioInd - Biotechnology and Bioengineering for improved Indus trial and Agro-Food processes, REF. NORTE-07-0124-FEDER-000028” Co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, FEDER. Grant Incentivo/EQB/LA0023/2014 from ON.2-O Novo Norte.