The (Mg,Fe) partition coefficients between Al-(Mg,Fe)SiO3 perovskite (Pv) and (Mg, Fe)O magnesiowustite (Mw) were inferred from Pv and Mw volumes measured by X-ray diffraction (European Synchrotron Radiation Facility, Grenoble), from 22 to 120 GPa, after laser annealing up to 2300 K. The (Mg,Fe) partition coefficient is found to decrease with increasing pressure and temperature (at moderate pressures) and with the additions of Al2O3. More iron is found in perovskite than in magnesiowustite at the highest pressures and temperatures. Artifacts possibly encountered during the calculation are discussed. Perovskite was found stable up to 120 GPa and 2200 K, with iron contents (Fe/(Mg+Fe)) up to 25%. The effects of Fe and Al2O3 on the orthorhombic distortion remain reduced. ¿ 2001 American Geophysical Union