A polyolefin composition having unusually low values of flexural modulus and shore hardness and comprising, in percent by weight: A) 15-40% of a copolymer of propylene with hexene-1 containing from 2.5 to 10% of hexene-1 and having Melt Flow Rate (MFR, measured according to ISO 1133, 230° C./2.16 Kg) from 0.5 to 100 g/10 min.; and B) 60-85% of an ethylene copolymer containing ethylene in a quantity equal to or lower than 40%, and having solubility in xylene at room temperature greater than 70%.