The purpose of the work was the assessment of the effect of alternative way of raw material preparation on the course and final results of maize mash ethanol fermentation. The material for investigation was dried maize grain of KB 1902 cultivar which, after grinding and moistening up to 15% of water content, was subjected to extrusion process in single-screw extruder of DN 20 type, produced by BRABENDER firm, applying extrusion temperatures 145°C, 180°C and 215°C. The extrudates obtained in the form of granules underwent grinding and mashing with the use of different raw material concentration, as well as changeable parameters of the mashing process, i.e. time of the process and doses of liquefying enzyme Termamyl 120L. Fermentation testes were conducted according to periodical method at the temperature of 37°C, introducing industrial distillery yeast Saccharomyces cerevisiae D2. In analogous conditions there were prepared control samples from ground, not extruded maize grain of KB 1902 cultivar. In the examined and control samples there were assessed the following parameters: dynamics of ethanol fermentation process, degree of sugars consumption, ethanol yield, as well as biomass physiological condition after the fermentation process. Fermentation time was related to mash density. It was possible to prove that the analysed changeable conditions of the process did not significantly affect the degree of sugars consumption (about 99 %) by yeast. More advantageous ethanol yield was obtained for the samples prepared from mashes featuring 200 g of raw material/kg. The best final results of fermentation – the highest ethanol yield (from 0.494 to 0.509 g ethanol/g starch) and the most satisfactory physiological condition of yeast after the process resulted from fermentation of maize flour extruded mashes at the temperature of 180°C.