With the emergence of experimental and commercial highly branched polymers (HBPs) having two or three dimensional morphologies with high peripheral functionality new opportunities have been created for formulating and tailoring new architectures for thermoset adhesives and related adhesion promoters. The authors studied a few adhesive systems previously. where the crosslinking agents had been either totally or partially replaced by the HBPs. In epoxy and polyurethane systems addition of poly-amido-amines (PAMAMs) HBPs, improved the mechanical and thermal properties of the adhesives due to increase of crosslinking density and formation of modified multiphase morphologies having high-energy absorption network. In the present study, the objective was to investigate the effects of HBP PAMAM primers on interfacial characteristics of epoxy and polyurethane bonded joints. using various substrates (Aluminum. Magnesium, plastics and fibers) prior and after exposure to a combination of heat and humidity. It was shown that the interfacial adhesion and the durability increase significantly (100-250%) in all the studied joints where PAMAMs were used for surface treatment.