Production of bioethanol from lignocellulosic biomass inevitably requires the biomass to be pretreated to remove lignin and produce fermentable sugars. This review is focused on the potential of ultrasound for improving the production of lignocellulosic bioethanol. Sonication can improve biomass pretreatment processes, the conversion of cellulose to fermentable sugars and also the fermentation step. Sonication can supplement existing biomass pretreatment methods to improve their efficacy and economics, or it can be used on its own. Cellulose hydrolysis to sugars can be improved with sonication. While overzealous sonication can be damaging to enzymes and cells, it can be effectively used to enhance enzymatic treatments and fermentation of sugars to bioethanol. Factors affecting sonicated processing of the lignocellulosic biomass to bioethanol are discussed.