Fermentation is an oldest method of food preservation and food nutritional value improving. It involves the concomitant action of one or more microorganisms, and yeasts are the one which play a significant role in African traditional fermented foods and beverages production. Traditional utilization of yeasts includes alcoholic beverages and fermented food production, but nowadays, with scientific methods developing, yeasts are implicated in medical, pharmaceutical, agriculture and other fields. Saccharomyces cerevisiae has been described as mankind?s most domesticated organism; it is always exploited in several fields to produce value-added products by raw matter biotransformation and also in industry. Several studies which have been realized on Candida utilis demonstrated it potential utilization for human consumption and as animal fobbed. Modern applications of yeasts have been greatly expanded beyond classical applications. Saccharomyces cerevisiae and other non ? Saccharomyces yeast today are increasingly used for the heterologous production of enzymes and pharmaceutical proteins, biofuel, medical drugs... Yeasts have important roles in environmental applications such as bioremediation, organic wastes biotransformation and removal of heavy metals from waste ? waters. Yeasts are also used in agriculture as biocontrol agents. Several chemical compounds can be produced using yeast as a biocatalyst. New developments in engineering yeast such as genetic modification have introduced novel capabilities to extend substrate range and produce new products so far yeast cannot produce. Yeast cell constituents at the nanoscale are the new fields of yeast nanobiotechnology thatnanotechniques are used for manipulation.