The phase relations in the pseudo-ternary system La2O3-SrO-Fe2O3 have been investigated in air. Isothermal sections at 1100 degrees and 1300 degrees C are presented based on X-ray diffraction and thermal analysis of annealed samples. Extended solid solubility was observed for the compounds Srn+1-vLavFenO3n+1-delta (n = 1, 2, 3, and infinity) and Sr1-xLaxFe12O19, while only limited solubility of La in Sr4-zLazFe6O13 +/-delta was observed. At high Fe2O3 content, a liquid with low La2O3 content was stable at 1300 degrees C.