Thin stillage is a liquid part of the fermentation mash remain- ing after the distillation of bioethanol. In our previous work [54,56], a possibility of thin stillage recirculation in the mashing process during the production of bioethanol from corn was investigated. Various process parameters such as fermentation rate, bioethanol yield, and the content of solids in stillage after distillation were evaluated. It was shown that as the amount of recirculated stillage increased (from 10% to 30%), higher bioetha- nol yields and starch utilization efficiencies were observed. The ethanol yield was increased from 97% to more than 100% [54], which could be explained by the fact that the stillage enriched the mashing slurry with amino acids, vitamins and the products of yeast cells degradation. The dry matter content in the slurry after the fermentation also increased with the increasing amount of the recirculated stillage. The dry matter remained after filtration of the slurry could be used as a cattle feed because of its high total protein content. This study [54] suggests that the recirculation of thin stillage should be the first and inexpensive step which should be undertaken in the bioethanol production process in order to decrease water consumption, and also the amount of the gener- ated waste water (e.g. thin stillage). In addition, the recirculation can result in higher ethanol yield and thus improved production economy.