The effect of the electric field on the dielectric and acoustic properties of Pb[(Mg1/3Nb2/3)(0.83)Ti-0.17]O-3 single crystals was investigated as functions of temperature and the electric field strength. The dielectric constant and the acoustic mode behaviors exhibited typical relaxor behaviors when there was no bias field. The longitudinal acoustic mode showed splitting under a moderate electric field of 1 kV/cm applied along the [001] direction, indicating coexistence of macroscopic/mesoscopic ferroelectric states and relaxor states. Further increase in the electric field up to 2 kV/cm induced a clear ferroelectric phase transition, which became smeared out due to the proximity of the electric field to the critical point. The electric field-temperature phase diagram of Pb[( Mg1/3Nb2/3)(0.83)Ti-0.17]O-3 was suggested based on the observed field-induced changes in the dielectric and the acoustic properties. (C) 2014 Elsevier B.V. All rights reserved.