In this study, the levels of natural and anthropogenic radioactivity in the sediment samples, collected from Beni Haroun Dam, were investigated using gamma-ray spectrometry. The results obtained for the 238 U, 232 Th series, 40 K natural element and 137 Cs anthropogenic radionuclide are discussed. To evaluate the radiological hazard of radioactivity in samples, the absorbed dose rate, the annual effective dose, the radium equivalent activity Raeq, the external and internal hazard indices Hex and Hin were calculated and presented in comparison with the data collected from different areas in the world.