The phase formation, sintering behavior, and magnetic properties of MgCuZn ferrites with composition Mg1-x-yCuyZnx+zFe2-zO4-z/2 with 0.4 = x = 0.8; 0 = y = 0.35; and 0 = z = 0.06 were investigated. Ferrite formation from starting oxides is complete at 900 degrees C. To guarantee sufficient densification at 900 degrees C substoichiometric compositions with small iron deficiency z = 0.02 are required. Substitution of Cu for Mg with 0 = y = 0.35 in a ferrite with x = 0.5 has minor effect on permeability only; however, the shrinkage is significantly shifted to temperatures as low as T < 900 degrees C. The permeability is mainly governed by the Zn concentration; mu increases from mu = 200 to 700 as x increases from x = 0.4 to 0.6, whereas simultaneously the Curie temperature is reduced from 180 degrees C to 40 degrees C, respectively. MgCuZn ferrites represent an interesting alternative to NiCuZn ferrites with large potential for multilayer applications.