In this book, a number of concepts have been proposed including the concept of "Anti-fuzzy AT-ideal" in the AT-algebra. The image of homomorphism formation and the reverse image for the Anti-fuzzy AT-ideal have been investigated and it hase been proved that the Cartesian product of anti-fuzzy AT-ideal of AT-algebra is an anti-fuzzy AT-ideal. The concept of "Intuitionistic fuzzy AT-ideal of AT-algebra" has also been introduced. The subalgebra, homomorphism and Cartesian product of intuitionistic fuzzy AT-ideal of AT-algebra have been investigated for this concept and the relation between the Anti-fuzzy AT-ideal and the intuitionistic fuzzy AT-ideal of AT-algebra has been shown.