The recycling of polymeric materials has gained increasing attention in the world because of economic and environmental considerations. Therefore, blends of low cost plastics such as polyolefins, polystyrene, and poly(vinyl chloride) present in polymeric waste are of particular interest. Among the different methods for recovering plastic residues, a two-step process, developed by two of the authors, permits the production of materials with controllable composition and homogeneous characteristics. This paper discusses the behavior of recycled 75/25 blends of low density polyethylene (LDPE) and high density polyethylene (HDPE) after exposure to various doses of gamma-irradiation (10-2000 kGy) in the presence of oxygen. Mechanical testing, differential scanning calorimetry, gel permeation chromatography, and infrared spectroscopy have been used to investigate the effects of gamma-irradiation on the polymer material. Mechanical strength was found to increase with irradiation doses up to 100 kGy, followed by a small decrease and a tendency to stabilization at higher doses. The degradation process is discussed.