A variety of fermented foods can be found widespread over the world. Some of them are described in this chapter, mainly to illustrate the complexity of biochemical, nutritional, and sensorial changes that result from an array of microbial activities in a range of raw materials. Recently, experiments with oncom-miso made from soybeans and oncom demonstrated increased anti-oxidative and antimutagenic activity associated with the enzymatic release of isoflavone-aglycones. Actinomucor elegans and A. taiwanensis are used as pure-culture starters in the manufacture of Chinese fu-ru, or sufu. The major functions of the fermentation of idli include the leavening of batter and improvement of flavor and nutritional value. There are two specific fermentation stages involved in soy sauce production, the first being an aerobic koji fermentation. Seed (tane) koji is produced by culturing single or mixed strains of Aspergillus oryzae or Aspergillus sojae on either steamed, polished rice or a mixture of wheat bran and soybean flour. Seed koji is added to a soybean-wheat mixture at a concentration of 0.1 to 0.2% and fermented into what is then simply called koji. The second stage is an anaerobic moromi or salt mash which undergoes lactic acid bacteria (LAB) and yeast (zygosaccharomyces rouxii) fermentations. Of interest to food microbiologists and sanitarians is the possibility of microorganisms' producing toxic substances or of pathogenic microorganisms' surviving during fermentation or storage of indigenous fermented foods.