A waveguide filter is provided having a plurality of asymmetrical corrugated resonators. The filter may also include an input section and an output section including a low-pass filter unit and a transformer unit. The low-pass filter unit includes a plurality of symmetrically corrugated slots, and the transformer unit includes at least one stepped transformer section for matching the filter to an external waveguide line. Each of the asymmetrically corrugated resonators may include a pair of opposed slots of different depth, a long slot and a short slot. The resonators provide at least one reflection zero and two transmission zeros to the frequency response of the filter, thus providing high-pass, band-pass and low-pass filter properties in a single filter structure.