The growing consumer demand for foods without chemical preservatives has focused efforts in the discovery of new natural additivies. Chitosan, which is one of these, have been of interest in the past few decades due to their potential broad range of industrial applications. Chitosan is obtained from chitin by a deacetylation process. Chitin is an aminopolysaccharide that comes from the shells of shellfish. Deacetylated chitin, or chitosan, is comprised of chains of D-glucosamine. When ingested, chitosan can be considered a dietary fibre. These biopolymers offer a wide range of unique applications such as enhancing of quality and storability of foodstuffs. The antimicrobial activity of chitosan has an important role in increasing of shelf-life of foods. Various studies showed that chitosan prevents microbial activity, targeting the different groups of microorganisms such as bacteria, fungi and yeasts This review summarizes the antimicrobial activity and food applications of chitosan.