Thermally induced coarsening of the chemically ordered domains in Pb(Mg1/3Ta2/3)O-3 (PMT) ceramics promotes the studying of dielectric behavior of the 1: 1 B-cations ordered PMN-style complex perovskites. In this work, PMT ceramics with different degrees of chemical order were prepared, and their dielectric, and ferroelectric properties of disordered and ordered ceramics were studied as a function of temperature, frequency, and electrical field. It was found that the weak field relaxor nature is insensitive to the chemical order, whereas some non-linear behaviors showed ordering-degree dependence at the low temperature range. (c) 2005 Elsevier Ltd. All rights reserved.