Thermodynamic analysis shows that (Mg,Fe)SiO3 perovskite is stable throughout the likely pressure, temperature and compositional regime of the Earth's mantle. The breakdown of perovskite to its constituent oxides appears unlikely, even under the extreme conditions of the core-mantle boundary. This reaction had been proposed to reconcile estimates of silicate melting with seismic observation and proposed geotherms. ¿ American Geophysical Union 1992