Using ultrasonic methods at ambient temperatures, for niobium carbide we determined the monocrystalline elastic stiffnesses:C11,C12, andC44in Voigt’s contracted notation. From these, we calculated the quasi‐isotropic (polycrystalline) elastic constants and the elastic Debye characteristic temperature. Results derived from a Blackman diagram suggest that ionic forces contribute significantly to the elastic constants and to interatomic bonding. This conclusion applies not only to NbC but also to other MX carbides with an NaCl‐type crystal structure.