Radiation shielding properties of concretes containing barite and colemanite in different rates were evaluated by using Ba-133 (80.99 and 303 key) and Am-241 (59.54 key) radioactive sources. Gamma rays were counted by a NaI(TI) detector with a resolution of 122 keV at 662 key. The study reveals that the concretes under research are effective than ordinary concrete for the attenuation of gamma rays. It was determined that the values of mean free path decreased with the increasing concentration of barite and colemanite and the linear attenuation coefficients increased with the increasing concentration of barite and colemanite in the concrete. Theoretical values were obtained by using Penelope and WinXCom computer programs and these were compared with the experimental results. (C) 2012 Elsevier Ltd. All rights reserved.