The domain structures of annealed (001)-oriented Pb(Mg1/3Nb2/3)O-3-x%PbTiO3(PMN-x%PT) crystals for x=10, 20, 30, 35, and 40 at.% have been investigated by polarized optical microscopy and scanning force microscopy in the piezoresponse mode. The results demonstrate the presence of a domain hierarchy on various length scales ranging from 40 nm to 0.1 mm, which varies with x. (C) 2004 American Institute of Physics.