For a group G, e(G) and sm(G) are denoted the set of orders of elements and the number of elements of order m in G, respectively. Let nse(G) = fsm(G) j m 2 e(G)g. An arbitrary nite group M is NSE characterization if, for every group G, the equality nse(G) = nse(M) implies that G = M. In this paper, we are going to show that the non-Abelian nite simple group A9, is characterizable by NSE.
