en Radiation Biology Radiation Biology تحقيق بديع Original Research <span style="font-weight: bold">Background:</span> Natural radioactivity in materials under certain conditions can reach the hazardous radiological levels. So, it becomes necessary to study the natural radioactivity in different materials to assess the dose for the population in order to know the health risks and to have a baseline for future changes in the environmental radioactivity due to human activities. <span style="font-weight: bold">Materials and Methods:</span> The present study deals with the measurement of radioactivity using “γ-ray spectrometry” from naturally occurring radionuclides in the soil, stone and sand samples used as building materials in North-Eastern Haryana state of India. The places are in the vicinity of Shivalik range of Himalayas. <span style="font-weight: bold">Results:</span> The activity concentrations for 226Ra, 232Th and 40K varied from 18±1.5 to 156±6Bqkg‑1, 23±1 to 300±5Bqkg‑1 and 32±0.5 to 1705±14 Bqkg‑1 respectively in various samples. The absorbed dose rate in soil, sand and stone samples is investigated at 1 m above ground level. Ra equivalents, Internal and external hazard indices have also been calculated. <span style="font-weight: bold">Conclusion:</span> The natural radioactivity levels measured in the samples under present study are below the recommended limits except for black stone (SB) and red stone (SR). However, these samples satisfy the universal standards. <span style="font-weight: bold">Iran. J. Radiat. Res., 2011 9(3): 187-194 </span> Absorbed dose, natural radioactivity, γ-ray spectrometry, Radium, thorium, potassium 187 194 http://ijrr.com/browse.php?a_code=A-10-1-401&slc_lang=en&sid=1 M. Gupta monika.kkr@gmail.com 790031947532846002407 790031947532846002407 Yes R.P. Chauhan 790031947532846002408 790031947532846002408 No