Epitaxial, perovskite Pb(Mg1/3Nb2/3)O3–PbTiO3 films were grown by metalorganic chemical vapor deposition under various deposition conditions and characterized by x-ray diffraction and transmission electron microscopy. Pyrochlore free films were obtained under all deposition conditions used in this study. Magnesium-rich growth conditions lead to the formation of a Mg-rich impurity phase in the films, embedded as coherent lamellae parallel to the growth direction. Depending on the growth conditions, a wide variation in the stoichiometry and volume fraction of this impurity phase was found between samples, whereas morphology and crystal structure were found to be very similar. © 2000 American Institute of Physics.