Thin strips of crosslinked linear high-density polyethylene were melted and then crystallized in contact by cooling to room temperature. The work required to peel the strips apart by pulling one strip away from the other at 90Π was found to be remarkably high, 5 to 30 kJ/m 2 , and in some cases the strips could not be separated in this way. However, adhesion measured in T-peeling was much lower, about onetenth as large. Adhesion was also fairly small, 200 to 600 J/m 2 , using other test methods designed to minimize bending strains. Thus, most of the work of separation is normally expended in bending, probably in plastic yielding of the outer layers of bent strips. However, even when bending energy losses were minimized, the residual adhesion was much greater than expected for Van der Waals bonding (about 0.05 J/m 2 ). Apparently, cocrystallization of molecular strands lying on either side of the interface greatly enhances the intrinsically low level of autohesion of amorphous polyethylene, probably by local yielding processes around the line of separation. Some effects of test temperature were also examined in T-peeling. Adhesion passed through a pronounced maximum at temperatures of 75-100ΠC before reducing to very low values in the melted state. This maximum was absent in tests with reduced bending. It is, therefore, attributed to extra work expended in plastic bending over a narrow range of temperature, probably due to a lower yield stress at these temperatures and not to an increase in the actual adhesion.