In ultrasonic grain size determination several techniques are in use. In this paper, the Ultrasonic Relative Attenuation (URA) method has been used to estimate the mean grain size of marble samples. Also, mean grain size versus first backwall echo height graphs have been plotted to see the direct relation between these two parameters. The results show less than 10% difference compared with values obtained in an optic microscope. In a comparison, mean grain size values of marbles determined by ultrasonic velocity methods are given. (c) 2005 Elsevier Ltd. All rights reserved.