The establishment of a polyethylene wear rate threshold for the development of osteolysis at the hip would allow surgeons to identify patients at risk for osteolysis and to implement selective, more frequent follow-up. We reviewed publications that met certain criteria for wear and osteolysis measurement. Based on this review, the incidence of osteolysis increases as the rate of wear increases. The literature indicates that osteolysis rarely is observed at a wear rate of <0.1 mm/y. We suggest that a practical wear rate threshold of 0.05 mm/y would eliminate osteolysis. This wear threshold suggests that the new cross-linked polyethylenes would reduce osteolysis, provided that in vivo wear rates mirror those observed in vitro. To facilitate future comparison of published data, we suggest that longitudinal wear studies adopt consistent edge detection-based wear measurement techniques and uniform osteolytic lesion classification and measurement schema. Copyright 2002, Elsevier Science (USA). All rights reserved.