The interplay among magnetism, charge mobility and structure in manganese oxide perovskites present excited in the last few years large scientific interest. Nevertheless several aspects on the physics of those compounds remain unclear. The evolution of the structure of La0.25Ca0.75MnO3 compounds as a function of pressure has been investigated by X-ray Powder diffraction in the high-pressure region, up to about 14 GPa. An anomalous and unexpected increasing of coherent Jahn-Teller distortions of MnO6 octahedron has been observed raising the pressure over 7 GPa suggesting deeper investigation in this region of the phase diagram.