AbstractIn this paper we introduce the notion of anti fuzzy ideals, anti fuzzy k−ideals of ordered semirings and we study the properties of anti fuzzy ideals, anti fuzzy k−ideals, homomorphic and anti homomorphic image and pre-image of fuzzy ideals, anti fuzzy ideals and anti fuzzy k−ideals of an ordered semiring. We characterize the ideals of an ordered semiring in terms of anti fuzzy k−ideals.