An endless power transmission belt having (1) a tension section; (2) a cushion section; and (3) a load-carrying section disposed between said tension section and cushion section; and the belt containing an elastomeric composition comprising (a) 100 parts of a rubber derived from (i) 50 to 100 parts by weight of an ethylene alpha olefin elastomer; and (ii) 0 to 50 parts by weight of a rubber selected from the group consisting of silicone rubber, polychloroprene, epichlorohydrin, acrylonitrile rubber, hydrogenated acrylonitrile rubber, zinc salts of unsaturated carboxylic acid ester grafted hydrogenated nitrile butadiene-elastomer, natural rubber, styrene-butadiene rubber, 1,4-trans-polybutadiene, ethylene-vinyl-acetate copolymer, ethylene methacrylate copolymers and terpolymers, chlorinated polyethylene, chlorosulfonated polyethylene, alkylated chloro sulfonated polyethylene, trans-polyoctenamer, polyacrylic rubber, and mixtures thereof; (b) from 1 to 30 parts by weight per 100 parts by weight of total rubber (phr) of a polybutadiene adduct of maleic acid anhydride.