A quintuple-mode wideband filter based on a single cavity is proposed. A pair of shorting pins is inserted into the cuboid cavity along the symmetry plane. The cavity filter is fed by a pair of coaxial cables and the inner conductor is inserted into the cavity with a circular disc at the end of the probe. The pair of inserted probes and the pair of shorting pins excite five resonant modes in the cavity. The proposed filter has the central frequency at 5.8 GHz with a bandwidth of 70%. Meanwhile the wideband filter has transmission zeros at the lower and upperstopbands to improve the selectivity and out-of-band performance. The measured insertion loss is <0.65 dB, and all measured results have a reasonably good agreement with the simulated results.