A dielectric waveguide filter comprising a block of dielectric material covered with an exterior layer of conductive material. A plurality of stacked resonators are defined in the block of dielectric material by one or more slots in the block of dielectric material and an interior layer of conductive material that separates the stacked resonators. First and second RF signal transmission windows in the interior layer of conductive material provide for both direct and cross-coupling RF signal transmission between the stacked resonators. In one embodiment, the waveguide filter is comprised of separate blocks of dielectric material each covered with an exterior layer of conductive material, each including one or more slots defining a plurality of resonators, and coupled together in a stacked relationship.