Blends of a Nynas 100 penetration-grade bitumen with a cis-polybutadiene, a butyl rubber, three polyisobutylenes of different molecular weights, a chlorinated-polyethylene, polychloroprene in latex form, and a polyurethane rubber (scrap Lycra) were prepared using a Z-blade masticator mixer at a temperature of about 180 degrees C. The blends contained between 10 and 40 pph (i.e., 9 and 29%) by weight of rubber. They were characterized by fluorescence optical microscopy, differential scanning calorimetry, and dynamic mechanical thermal analysis. The bitumen rich phases provided the matrix in most of these systems, polymer rich extensive phases being formed with butyl rubber, and low- and moderate-molecular-weight poly(isobutylenes) when the proportion rose above 30 pph, and for the poly(cis-butadiene) and chlorinated polyethylene system only when the proportion rose above 40 pph, according to the tan delta plots. Only glass transitions were associated with polymer-rich phases, and there were some melting transitions from paraffinic wax components ejected from the bitumen-rich phases. Below room temperature the modulus of blends of polybutadiene, chlorinated polyethylene, and the polyurethane rubber were similar to that of the bitumen; but those of the other polymers were stiffer by a factor of 50, perhaps because of a rearrangement of the asphaltenes. The softer blends, particularly the first two named above, had loss processes (with tan delta > 0.5) ranging over 200 degrees C or more.