Background: This study was designed to compare antimicrobial activity of Alginate and Alginate-resistant starch micro particles against Listeria monocytogenes.Methods: Nisin loaded micro particles were prepared by a w/o-emulsion external cross-linking procedure with three weight ratio of nisin to Alginate (4: 1, 2: 1 and 1: 1). For comparison of the antimicrobial activity of nisin encapsulated in Alginate and Alginate-resistant starch micro particles, the release of nisin from micro particles was studied in distilled water as release medium and activity of released nisin was determined using the food pathogen Listeria monocytogenes ATCC 19117in agar diffusion test. Three wells of 6 mm diameter were punched into the agar on each plate (that seeded by 100ml of an overnight broth culture containing 107-108 CFU/ml of the test organisms) and lyophilized microcapsules were loaded into wells. Plates were incubated at 37oC for 24 h. The diameter of inhibition zone was then measured. The amount of released nisin from micro particles was determined using bacteriocin standard curve.Results: The nisin release from all formulations occurs in two stages: first, a rapid release phase, which corresponds to nisin being physically entrapped in the surface of micro particles, and second, the nisin being gradually released, until the nisin content was constant (66-76% in Alg microparticles and 61-70% in Alg-RS micro particles). The releasing of nisin depended on the initial bacteriocin content. When the nisin content increased, the amount of released nisin was found to decrease In addition, lower rate releases were found in Alginate- resistant starch micro particles. This lower rate release for Alginate-resistant micro particles in comparison to Alginate micro particles was attributed to the presence of resistant starch in Alginate matrix that retarded the release of nisin.Conclusion: Cumulative release of nisin from Alginate-resistant starch micro particles occur in a controlled manner and antimicrobial activity of nisin in this micro particle is maintained for a longer period of time which this long lasting antimicrobial activity useful in food matrixes.