The broiler industry supplies quality protein, which is in constant development. It seeks productive strategies that improve production, health, growth, and survival and reduce the poultry industry's diseases, stress, and long-term environmental impact. Broiler chickens are exposed to numerous microorganisms that alter production, and this is an opportunity for yeasts to promote the growth of organisms, stimulate the immune system, improve health, promote changes in intestinal structure, and inhibit pathogens. This review summarizes the current knowledge and effect of active yeast species on raising chickens, nutrition, immunity, digestibility, changes in intestinal structure, and pathogens on those organisms. Due to their nutritional value, active yeasts are used as natural and alternative ingredients in broiler chickens. They are a source of b-glucans, chitin, nucleic acids, mannan-oli...