In this study the natural radioactivity in marble samples used in Turkey was measured by means of gamma spectrometry. The results showed that the specific activities of Ra-226, Th-232 and K-40 ranged from 10 to 92 Bq kg(-1), from 4 to 122 Bq kg(-1) and from 28 to 676 Bq kg(-1), respectively. The radiological hazards in marble samples due to the natural radioactivity were inferred from calculations of radium equivalent activities (Ra-eq), indoor absorbed dose rate in air values, the annual effective dose and gamma and alpha indexes. These radiological parameters were evaluated and compared with the internationally recommended values. The measurements showed that marble samples used in Turkey have low level of natural radioactivity; therefore, the use of these types of marble in dwellings is safe for inhabitants. Mass attenuation coefficients (mu/rho) were obtained both experimentally and theoretically for different marble samples produced in Turkey by using gamma-ray transmission method. Experimental values showed a good agreement with the theoretical values. (c) 2010 Elsevier Ltd. All rights reserved.