A series of La substituted MgCuZn ferrite powders (Mg0.35Cu 0.05Zn0.60LaxFe2-xO 4 with, x = 0.00, 0.01, 0.03 and 0.05) were synthesized by a novel microwave sintering method. The effect of La-substitution on the structural, physical and magnetic properties has been studied. X-ray diffraction confirmed the formation of single phase cubic spinel lattice for all the compositions studied. The lattice constant increased with increasing La content, might be attributed to the larger ionic radius of La3+ than the Fe 3+. X-ray density of each sample is higher than the corresponding bulk density of sintered sample. The grain size was estimated using SEM micrographs. Room temperature saturation magnetization and magnetic initial permeability were found to increase with La substitution in Fe up to x = 0.01 and then decreased. The role of lanthanum in modifying structural and magnetic properties of microwave treated MgCuZn ferrites system has been explained suitable.© 2013 Elsevier Ltd. All rights reserved.