The increase in rock engineering projects over the last decade, has made an increase in the importance of the determination of the rock mass parameters. Although properties of rock material are usually determined at laboratory, it can also be determined by special in situ tests. These in situ tests are both expensive and time consuming. Therefore, empirical equations are developed to estimate rock mass properties by several researchers. In numerical modelling, rock mass properties are important. Furthermore controlling the results of models, making back analysis and taking the feedback are very important. Comparison of different empirical equations of deformation modulus of rock mass suggested by different researchers by using field displacement measurements and numerical modelling results is aimed in this study. (C) 2012 Elsevier B.V. All rights reserved.