Nonreciprocal properties of magnetoplasmons in the imperfect magnetised semiconductor films sandwiched between the
dielectric layers have been explored. It is demonstrated that losses qualitatively alter the eigenwave spectrum and the
properties of magnetoplasmons. The effect of the structure parameters is analysed, and it is shown that strongly
nonreciprocal attenuation of the eigenmodes in asymmetric structures may result in the unidirectional propagation of
magnetoplasmonic modes. The competing effects of the reciprocal and nonreciprocal field displacement, and the impact
of the field and power flux distributions on the mechanisms of nonreciprocal and unidirectional magnetoplasmon
propagation in the imperfect semiconductor films are discussed.