Ethylene polymer composition comprising, all percent amounts being by weight: A) 30-60% of an ethylene polymer containing 10% or less, referred to the weight of A), of a fraction XSA soluble in xylene at 25° C.; B) 40-70% of a copolymer of ethylene with at least one olefin of formula HC2═CHR, where R is a alkyl radical, linear or branched, having from 2 to 8 carbon atoms, containing 65-90% of ethylene and 55-15% of a fraction XSB soluble in xylene at 25° C., both the ethylene of the copolymer and XSB amounts being referred to the weight of B), the intrinsic viscosity [η] of the XSB fraction ranging from 0.8 to 3.2 dl/g; wherein the amounts of A) and B) are referred to the total weight of A)+B).