In this note, we define the antisimple radical, A(M), of a Γ-ring M. A(M) is shown to be a special radical, and two characterizations of antisimple rings due to Szész are extended to Γ-rings. If R is the right operator ring of M, then A(R)* = A(M), where A(R) is the antisimple radical of R. If m,n are positive integers, then A(Mmn) = (A(M))mn, where Mmndenotes the group m x n matrices over M, considered as a Γnm-ring with the operations of matrix addition and multiplication.