Abstract
An n-exact category is a pair consisting of an additive category and a class of sequences with n + 2 terms satisfying certain axioms. We introduce n-weakly idempotent complete categories. Then we prove that an additive n-weakly idempotent complete category together with the class C-n of all contractible sequences with n + 2 terms is an n-exact category. Some properties of the class C-n are also discussed.