Аннотация:A giant magnetoresistance (MR) is found in the CuCr1.6Sb0.4S4 semiconductor spinel, consisting of a solid solution of CuCr1.5Sb0.5S4 antiferromagnet (AF) and the CuCr2S4 fetromagnet. This MR is negative and isotropic. Its value is equal to 74% at temperature T = 3 K (magnetic field H = 38 T) and decreases with decreasing T. Magnetization isotherms are the superposition of a linear part, as for AF, and a small spontaneous magnetization. Therefore we assume that the sample is an AF in which droplets with spontaneous magnetization are disposed. Nagaev showed that giant MR in doped AF semiconductors is explained by similar magnetic two-phase state in which all the electrons are concentrated in droplets because of the energy gain in s-d exchnge.