Experimental study of microwave giant magnetoresistive effect in wave reflection has been carried out in frequency range from 26 to 38 GHz. The magnitude of the effect is obtained and its magnetic field dependence is defined. The experiments are carried out with (CoFe)/Cu superlattices, which have giant magnetoresistance. Calculations of the magnetic field dependence of microwave reflection coefficient are fulfilled. The measured values of reflection coefficient variations are found to be greater than the calculated ones. This difference is connected with approximation within which the superlattice is replaced by the uniform metallic plate in calculations. A frequency dependence of microwave giant magnetoresistive effect in reflection is also observed. This dependence is explained by the influence of the waveguide impedance where the sample is placed in measurements.