Temperature and field dependent investigations of the longitudinal electromechanical properties of [001]- and [110]-oriented 0.955Pb(Zn1/3Nb2/3)O-3-0.045PbTiO(3) single crystals have been performed. Electromechanical equivalence was found between [001] and [110] orientations in the ferroelectric rhombohedral FEr phase region, but not in the ferroelectric tetragonal FEt one. A dc bias of 0.4 MV/m did not affect this equivalence. Softening of the dielectric constant (K), piezoelectric coefficient (d(33)), and Young's modulus (Y) were observed along both the [001] and [110] orientations in the FEr phase region on heating towards the FEt one. Above the FEr-FEt phase transition, a significant anisotropy was observed in the electromechanical and elastic coefficients. These results demonstrate that the enhanced length extensional (33-mode) electromechanical coupling k(33) of rhombohedral crystals far from the morphotropic phase boundary is not constrained to the <001> orientation, but rather to the (110) plane. (C) 2004 American Institute of Physics.