The five independent elastic constants of hexagonal CaMg2have been determined by the ultrasonic pulse‐echo technique over the temperature range, 100–300°K. In keeping with normal metallic behavior, the measured elastic constants do not fit the Cauchy relations. The degree of elastic isotropy is high, particularly so with respect to compressive or tensile strains. The compressibility of the compound is slightly less than the average of the compressibilities of the constituent elements. This compressibility behavior is reasonable on the basis of the small negative heat and volume of formation of the compound.