Glide symmetry in periodic structures introduces several advantages such as low dispersion, wider stopbands, and higher levels of anisotropy. Here, we propose the use of glide symmetry in dielectric-filled corrugated rectangular waveguides. The operation of these filled waveguides is studied by means of a multimodal transfer-matrix approach that carries out a Bloch analysis of the corresponding unit cell to obtain the dispersion diagram of the structure (both the phase shift and the attenuation rate). In this specific configuration, glide symmetry is found to provide a wider backward passband below the cutoff of the non-corrugated housing waveguide.