A domain decomposition method (DDM) is presented for the solution of electromagnetic scattering problems by inhomogeneous 3-D bodies. The computational domain is partitioned into concentric subdomains on the interfaces of which Robin-type transmission conditions are prescribed. On the outer boundary terminating the computational domain, the radiation condition is taken into account by prescribing either an integral equation (IE) or an absorbing boundary condition. In the former case, the DDM decouples the inner problems, that correspond to the solution of Maxwell's equations inside each subdomain, from the outer problem solved by employing the IE. The convergence of the DDM algorithm to the solutions of the original problems is demonstrated when the dielectric permittivity and magnetic permeability tensors characterizing the inhomogeneous medium are those of passive materials.