The stress- and strain-relaxation behavior of lead zirconate titanate based ceramics is studied by using the three-point bending test. The relaxation behavior has been explained based on the domain reorientation mechanism. It is found that the stress relaxation behavior obeys a logarithmic time law. It has also been experimentally confirmed that above the Curie temperature where all the domains disappear, there is no relaxation in the ferroelectric ceramics. (C) 2002 Elsevier Science B.V. All rights reserved.