The six independent elastic constants of a single crystal of tetragonal MgF2with rutile structure were measured ultrasonically at room temperature from ambient conditions to 10 kbar. The values at 1 bar and 10 kbar are (in 1011dyn/cm2)C11: 14.081 (1 bar), 14.597 (10 kbar);C12: 9.003 (1 bar), 9.569 (10 kbar);C13: 6.417 (1 bar), 6.543 (10 kbar);C22: 20.490 (1 bar), 21.094 (10 kbar);C44: 5.664 (1 bar), 5.768 (10 kbar);C66: 9.560 (1 bar), 9.964 (10 kbar).CS=(C11−C12)/2 softens with pressure, whileC44shows a weak pressure dependence. Similar behavior has been observed in NiF2, ZnF2, TiO2, and in the distorted rutile crystal TeO2. The reported pressure induced transition from tetragonal MgF2to distorted fluorite type observed at 250 kbar using x‐ray scattering is not anticipated by the softening ofCSwhich would lead to an orthorhombic distortion.