The invention relates to an improved process of producing a fermentation product, such as ethanol, from starch-containing material using an increased dosage of alpha-amylase during liquefaction, which results in increased conversion of dextrins compared to conventional processes, and/or a reduced dosage of carbohydrate-generating enzyme during simultaneous saccharification and fermentation compared to a conventional process carried out at the same conditions. A process of the invention results in an increased yield. The invention also relates to an improved process of producing a fermentation product resulting in substantially the same yield as a conventional process, wherein reduced dosage of carbohydrate-source generating enzyme is used during simultaneous saccharification and fermentation.