This work aimed to study the effects of radiation on the properties of ethylene propylene diene terpolymer/chlorosulfonated polyethylene rubber blend reinforced with 50 phr of carbon black and cross-linked either with sulfur/tetramethylthiuram disulfide or dicumyl peroxide. Irradiation doses were 100, 200, and 400 kGy. It was observed that doses higher than 200 kGy practically destroy the assessed properties of all obtained elastomeric materials, irrespective of used curing system. However, samples cured with sulfur showed a pronounced decrease in mechanical properties.