Abstract-An experimental investigation of radiation shielding properties of high performance concretes (HPCs) was mad under effect of different variables. HPCs were produced from different normal and heavyweight aggregate with three low water-to-cementitious materials ratios (w/cm) to obtain different compressive strengths. The linear attenuation coefficients were measured at 0.663 MeV γ-rays energy of 137 Cs radioactive using NaI (Tl) scintillation detector. It was found that the compressive strength of heavyweight HPCs plays an important role in enhancing the attenuation of γ-rays. The compressive strength and attenuation of γ-rays have a near to linear relation. While in the normal concrete, the strength has no effect on the attenuation of γ-radiation. The mass attenuation coefficients were also compared with the values obtained by the United States National Institute of Standards and Technology (NIST). The comparison showed a reasonable agreement. It was observed that the attenuation of γ-rays is considerably affected by concrete density.Index Terms-High performance concrete, γ-attenuation coefficients, aggregate types, compressive strength, water-to-cementatious materials ratio.