A method is proposed for solving the wave diffraction problem by employing a system ofNspace-localized inhomogeneities in a longitudinally homogeneous waveguide. The method combines integral equations and eigenfunction methods. As an illustration of this method, acoustic diffraction is calculated from a system ofN,different, parallel cylinders arbitrarily placed in a liquid layer. The problem is reduced to a system of2Nintegral-functional equations relative to fields excited in elastic bodies and sources of scattered waves on the surface of the cylinders. Standard methods may be used for solving the systems of equations. Numerical solutions are found for various versions of the system of elastic cylinders(N=1,2)in a liquid layer with perfectly “soft” and “hard” walls. The method allows: (1) the calculation of the scattering matrix for reflected and transmitted waves with any given accuracy; (2) the construction of the amplitude-frequency and the phase-frequency characteristics for the matrix elements; and (3) the calculation of the distribution of field sources on the surface of each cylinder and the scattered wave field both in the near and far zones.