The atomic structure of ordered domains inBa(Mg1/3Nb2/3)O3and La-doped and undopedPb(Mg1/3Nb2/3)O3is studied by high-resolution Z-contrast imaging. The ordered domain structure in both doped and undopedPb(Mg1/3Nb2/3)O3is determined to be in agreement with the charge balanced random-layer model and inconsistent with the space-charge model. It is shown that La doping inPb(Mg1/3Nb2/3)O3enhances not only the domain size but also the degree of ordering. ©1998 American Institute of Physics.