A polypropylene composition comprising (percent by weight) (a) 50-77% of a crystalline propylene polymer having an amount of isotactic pentads (mmmm), measured by 13C-MNR on the fraction insoluble in xylene at 25° C., higher than 97.5 molar % and a polydispersity index ranging from 4 to 10; (b) 13-28% of an elastomeric copolymer of ethylene and propylene, the copolymer having an amount of recurring units deriving from ethylene ranging from 30 to 70% and being partially soluble in xylene at ambient temperature, the polymer fraction soluble in xylene at ambient temperature having an intrinsic viscosity value ranging from 2 to 4 dl/g; and (c) 10-22% of polyethylene having an intrinsic viscosity value ranging from 1 to 3 dl/g, in said composition component (b) plus component (c) being in amounts of at least 25 wt %. The polymer composition exhibits good impact resistant, whitening resistance and relatively low stiffness.