Department of polymer processing, Iran polymer and petrochemical institute, Tehran, Iran Shielding radiation from both x-rays and gamma-rays is important for personnel in medical fields, for example, interventional radiology, nuclear power stations, and other facilities where radiation is involved. Lead is known for its effective shielding property; however heaviness and toxicity are its main drawback. In this study effectiveness of non-lead polymeric composite materials, which include high-atomic-number (powders of spherical W and lamellar MoS2)/or known barrier elements to absorb photons from the radiations (lamellar B4C) was evaluated. HDPE and particulate fillers were melt mixed in an internal mixer. Goodness of dispersion was manifested via SEM and EDX images. Radiation attenuation capability of samples was examined with direct diagnostic x-ray exposure. Dynamic rheology measurements were carried out to evaluate viscoelastic properties, necessary in shaping process operations. Mechanical and thermal properties were further investigated from the product performance point of view. Results demonstrated that the flexible composite sheet of HDPE/45% (wt) W provided comparable x-ray absorption to non-flexible lead sheet but much lighter in weight. Significant difference was observed between flow characteristics and yield strength of composite materials of highly loaded spherical and lamellar particles. Melt viscoelastic behavior of former was similar to that of neat matrix melt. POLYM. COMPOS., 00:000-000, 2017.