Аннотация:Generation of paramagnetic particles in gamma-irradiated microheterogeneous butadiene-styrene block copolymers was examined using ESR. Negative deviation of radiation-induced yield of paramagnetic particles from the additivity pattern was found to be maximal for samples with high PS content (60 - 80%). The analysis of the composition of paramagnetic species led to a conclusion that the electrons generated in the PS matrix are involved in interfacial reactions with allylic radicals of polybutadiene domains.