The in-vitro wear behavior in the presence of abrasive particles was determined for two highly crosslinked ultrahigh molecular weight polyethylenes (HXPE), one in clinical application for hips and the other for knees. The wear studies were performed in joint simulators and were largely comparative, with conventional ultrahigh molecular weight polyethylene (UHMWPE) gamma irradiated 37 kGy in nitrogen used as the control. The test methodology used for these three-body wear tests was developed in-house. It was found that the wear advantage of the HXPEs relative to the conventional UHMWPE observed under clean conditions is largely preserved in the presence of the abrasive particles used (alumina and bone cement for hips, bone cement for knees) under the test conditions. These results suggest that the surface molecular chain orientation-inhibition mechanism proposed to account for the increased wear resistance of highly crosslinked polyethylenes undergoing micro adhesive/abrasive wear is still operational even when a thicker surface layer is disturbed in the presence of abrasive particles. Therefore, the wear of the UHMWPE is not simply dependent on the bulk mechanical properties of the UHMWPE. The higher than expected wear of the 22 mm hip liners compared to the 32 mm liners in the presence of abrasive particles suggests that the wear rate of the UHMWPE becomes stress dependent rather than load dependent for sufficiently high stresses.