Abstract: A rubber composition comprising the following component (A) 30-95 parts by weight, component (B) 5-70 parts by weight, component (C) 0.1-15 parts by weight and component (D) 0.01-15 parts by weight, and comprising no reinforcing filler (where the total of component (A) and component (B) is 100 parts by weight).

Abstract: A rubber composition containing no reinforcing agent, which comprises (A) 55 to 95 parts by weight of an ethylene-?-olefin-non-conjugated diene copolymer rubber, (B) 5 to 45 parts by weight of a natural rubber, and (C) 0.1 to 15 parts by weight of an organic peroxide, wherein the total amount of the components (A) and (B) is 100 parts by weight; a process for producing a rubber composition comprising the steps of (1) kneading at least said components (A) and (B), and (2) mixing at least the kneaded product with said component (C); a process for producing a molded article containing a vulcanized rubber composition, which comprises the above kneading step (1), the above mixing step (2), and the step (3) of molding the rubber composition at elevated temperature; and a vibration-proof material which comprises a molded article containing a vulcanized rubber composition produced according to the above-mentioned process.