A new class of waveguides, chiroferrite filled coupled guides, (CFCL) is introduced which exhibit some novel nonreciprocal properties owing to the interaction effects between gyrotropy and chirality. These CFCL structures consist of two parallel guides coupled via a chiroferrite or ferrite-chiral composite medium. The phenomena occurring in CFCL in the presence of two propagating even and odd modes are analysed using the coupled mode method. Two nonreciprocal phenomena are observed. It is found that the polarization plane of the electromagnetic wave propagating in the structure rotates with different rotation angle and its polarization ellipticity having different values when the magnetization or propagation direction is reversed. These nonreciprocal behaviours show the feasibility of CFCL structures as a new type of nonreciprocal devices for millimeter and optical wave applications. The results of the analysis are applied to derive the scattering matrix of a section of symmetrical CFCL. The conditions indispensable for nonreciprocal operation of the structure are obtained.