High quality Y3Fe5O12/Gd3Ga5O12(YIG/GGG) superlattices have been grown on (111)GGG substrates by pulsed laser deposition. The superlattices are investigated with the thickness of the YIG layer varied from six to one unit cells while keeping the GGG layer fixed at one unit cell. The thicknesses of the YIG and GGG layers are confirmed with grazing angle x‐ray reflectivity (GAXR). The good quality of the samples is indicated by the small interface roughness, no more than 6 A˚, also measured with GAXR. While the magnetization of the samples decreases when the thickness of the YIG layer is decreased, the superlattice remains magnetic even when the YIG layer is only one unit cell. Ferrimagnetic resonance indicates that there exists a surface anisotropy favoring in‐plane magnetization. ©1996 American Institute of Physics.