We analyze the rheology of a bitumen modified with 5% of high-and low-density polyethylene and their respective blends with ethylene/propylene/ethylidene norbornene. A broad mechanical relaxation, observed around 30 degreesC, is associated with the collapse of a compact structure, constituted by asphaltene particles surrounded by solid resin. The addition of polymer to bitumen does not modify this relaxation. Above 30 degreesC the dynamic functions decrease as: HDPE/bitumen > HDPE-EPDM/bitumen > LDPE-EPDM/bitumen > EPDM/bitumen > LDPE/bitumen > bitumen. We assume that the degree of polymer-bitumen interaction, follows the same order. This is in apparent contradiction with the results one could expect from solubility considerations.