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