In this paper the far field pattern for the acoustic scattering waves in the nonhomogeneous medium is studied. Both the eigenvalue for the far field operator and the identity operator for the scattering operator are investigated. Also, this paper the inverse scattering problem is studied. All this researches, density of the absorbing medium rho is an element of C-1(R-3) is assumed that del(rho) not equal 0. (C) 2003 Elsevier Inc. All rights reserved.