Encapsulation technologies are used to keep probiotic cell viable throughout storage, commercialization and use in food products, so that these cells are active during their passage through the gastrointestinal tract. This review describes the most common encapsulation technologies and encapsulation materials used for maintaining the viability of probiotic bacteria under adverse external conditions. Illustrations are presented to facilitate the understanding of the various encapsulation methodologies. Supercritical fluid technologies for encapsulation as well as new wall materials are discussed. It is concluded that several variables affect the viability of encapsulated probiotic cells and therefore optimization tools including response, genetic algorithms, quadratic sequential programming are needed for appropriate material selection. Key words: Lactic acid bacteria, lyophilization, spray drying, extrusion, cellular viability.