Let R be a ring with identity, be the ring of n×n matrices over R, and for each be a right ideal of R such that for all In the present paper we determine the structure of derivations of certain subrings of of the form consisting of all matrices with for all Using this result we determine the structure of derivations of semisimple rings. Note that the latter result is an extension of a result of S.P. Coelho and C.P. Milies and a result of S. Jøndrup.

Keywords: with for all Using this result we determine