we define and studyco-noetherian dimension of rings for which the injective envelopeof simple modules have finite krull-dimension. this is a moritainvariant dimension that measures how far the ring is from beingco-noetherian. the co-noetherian dimension of certain rings,including commutative rings, are determined. it is shown that the class ${mathcal w}_n$ of rings with co-noetherian dimension...