The activity concentrations of (226)Ra, (232)Th, and (40)K in lime and gypsum samples used as building materials in Turkey were measured using gamma spectrometry. The mean activity concentrations of (226)Ra, (232)Th, and (40)K were found to be 38 +/- 16, 20 +/- 9, and 156 +/- 54 Bq kg (-aEuro parts per thousand 1) for lime and found to be 17 +/- 6, 13 +/- 5, and 429 +/- 24 Bq kg (-aEuro parts per thousand 1) for gypsum, respectively. The radiological hazards due to the natural radioactivity in the samples were inferred from calculations of radium equivalent activities (Ra(eq)), indoor absorbed dose rate in the air, the annual effective dose, and gamma and alpha indices. These radiological parameters were evaluated and compared with the internationally recommended limits. The experimental mass attenuation coefficients (mu/rho) of the samples were determined in the energy range 81-1,332 keV. The experimental mass attenuation coefficients were compared with theoretical values obtained using XCOM. It is found that the calculated values and the experimental results are in good agreement.