Abstract: Objective: To evaluate the influence of the expression of osteolytic cytokines induced by micrometer-diameter wear particles (Ti-6Al-4V and UHMWPE). Methods: Filtration air was injected subcutaneously into rats'back 6 times ( 3ml qod ). After a week, wear particles suspension (Group A: Ti-6Al-4V, Group B: UHMWPE) or physiological saline(Group C) was injected into air pouch tissues. After 14 days, pouch tissues were obtained from killed rats, and were weighted, wax embedded and stained with hematoxylin and eosin, observed under microscope. AKP of serium with Automated Biochemical Analyzer, IL-6 and TNF-α expression with immunohistochemical method, and mRNA expression of extracellular matrix metalloproteinase inducer (EMMPRIN) with real-time Polymerase Chain Reaction method were detected. Results: Air pouch tissues were similar to limiting membrane of periprothesis tissue in the cases of aseptic loosening. As to pouch tissue weight, there was a significant increase in group B than in group C (p<0.05). Microscopy illustrated a large amount of phagocytes in group A and B. The activities of AKP, expression of IL-6 and mRNA expression of EMMPRIN in group A and group B were higher than in group C (P<0.05). Conclusions: The two wear particles both can modulate the production and expression of osteolytic cytokines, lead to aseptic loosening.