A heterophasic polyolefin composition comprising: (A) 50-0% of a crystalline propylene polymer; (B) 5-20% of a first elastomeric copolymer of ethylene with at least a C3-C8 α-olefin comonomer; and (C) 10-45% of a second elastomeric copolymer of ethylene with at least a C3-C8 α-olefin comonomer; wherein the ratio between the ethylene content of the fraction insoluble in xylene at room temperature (C2xif) multiplied by the weight percentage of the fraction insoluble in xylene at room temperature (% XIF) and the ethylene content of the fraction soluble in xylene at room temperature (C2xsf) multiplied by the weight percentage of fraction soluble in xylene at room temperature (% SXF) satisfies the following relation (I): C 2 ⁢ xif × % ⁢ XIF C 2 ⁢ xsf × % ⁢ SXF > 0.01 ⁢ x + 0.261 , wherein x is the total amount of ethylene.