Deformation modulus of a rock mass (Em) is one of the most important design parameters in construction of rock engineering projects such as underground excavations. However, difficulties are frequently encountered during in-situ tests which are also time-consuming and expensive for determining this parameter. Although Em is often estimated indirectly from proposed equations by different researchers, many of these equations cannot be used in case of problematic rock conditions (thinly bedded, highly jointed rock masses, etc.) as high quality core samples are required. This study aims to explore more practical and useful equation for Em estimation using Rock Quality Designation (RQD) and point load index values. Comparisons were made between available empirical equations and the proposed Em equation in terms of the estimation capacity. Multiple comparison tests (ANOVA) showed that Em can be reliably estimated using proposed equation especially at the preliminary stages of projects. (C) 2015 Published by Elsevier B.V. on behalf of China University of Mining & Technology.