The Authors present the results of an experimental investigation that was carried out in order to assess the effects of Refuse Derived Plastics used as additives in bituminous mixtures. Two types of low-density polyethylene (LDPE) sampled from a recycling plant were considered in the study. They were added in various percentages to a base bitumen and thereafter used for the preparation of bituminous mixtures for binder courses. The bitumen-additive combinations were subjected to empirical and rheological testing. The properties of the mixtures were evaluated by means of repeated-load indirect tensile tests and standard quality assurance tests (Marshall and indirect tensile strength tests). Moreover, a full volumetric characterisation was performed for all mixtures. General conclusions were drawn in order to select the optimal plastic type and dosag