The dynamic properties of rubber bearings frequently used as isolators in structures could be significantly deteriorated because of the change of microstructure in rubber caused by cyclic compression and thermal aging. As a result, a catastrophic failure of bridges and buildings unexpectedly occurs when they are subjected to earthquake attack. Here, the dynamic properties of neoprene rubber bearings before and after different cycles of compressive loading or various periods of thermal aging were first measured and compared to each other. On the basis of the experimental results, the effects of cyclic compression and thermal aging on the stiffness, energy absorption, and equivalent viscous damping coefficient of neoprene rubber bearings are investigated. It is found that the deterioration of dynamic properties of neoprene rubber bearings caused by either cyclic compression or by thermal aging is significant and should be taken into account in designing rubber bearings. (c) 2007 Wiley Periodicals, Inc.