Let H be a complex separable Hilbert space and let B(H) be the algebra of all bounded linear operator on H. Let {A1,…..,An} and {B1,…..,Bn} be two commuting families of self-adjoint operators in B(H). In this paper we are concerned with the investigation of the spectrum of the elementary type operator ?:B(H)--->B(H) defined by ?(X) = Σ Ai XBi for all x in B(H). More precisely, we show that Sp(?;B (B(H))) =Formula is missing