Numerical results obtained using a full-wave hybrid technique (comprising a new formulation of the coupled-mode method and the mode-matching method) for treating 3-D isotropic- chiral-material discontinuities in rectangular wave guides with perfect electrically conducting walls were compared with experimental data. For that purpose, samples of an isotropic chiral material were manufactured as composite materials. These samples were then fully characterized in the X-band. The measured constitutive parameters were used in the full-wave hybrid technique to predict the scattering parameters of three different structures-each a waveguide filled partially with the isotropic chiral material. The scattering parameters were also measured. The predicted and measured scattering parameters were in reasonably good agreement.