This study demonstrates the feasibility of using a simple method to measure the resonant fundamental frequency for determining the MOE (dynamic Young’s modulus) of lime and cement mortars. The procedure follows the instructions stated in the UNE-EN ISO 12680-1 standard for refractory products although in this study the instructions are applied to standardized RILEM 4x4x16 cm test samples made of lime and cement mortars. The simplicity of the procedure as well as its correlation to other measured variables, suggest that it can be widely applied in studies about the evolution of the physical characteristics in lime mortars, such as mechanical strength, static Young’s modulus, carbonation depth, etc