To study the etiology and the mechanisms of osteolysis induced by polyethylene particles. Methods A rabbit model of resorption of bone at the bone-prosthesis interface induced by polyethylene particles was established. The pathological findings were studied. In vitro human rnonocytes were cultured and stimulated by polyethylene particles. The levels of TNF-a of the supernats were measured by radioimmunoassay. Results There was a layer of interface membrane that contained numbers of maerophages and giant cells around the prosthesis, and there was evidence of active bone resorption and osteolysis. The polyethylene particles were found in the interfacemembrane and engulfed by macrophages. The levels of TNF-a were significantly increased when the monocytes were ex posed to polyethylene particles (P<0.01). Conclusion There is a positive relationship between the accumulation of polyethylene particles and subsequent resorption of bone. The polyethylene particles can stimulate monocytes to produce more TNF-a.