Aim To examine the roles of urokinase-type plasminogen activator receptor(uPAR),a cellular receptor for the urokinase-type plasminogen activator(uPA) in monocytic migration induced by Monocyte chemotactic protein-1(MCP-1). Methods Monocytes were separated and purified by density gradient centrifugation and adhering assay.MCP-1 were added into each lower chamber of TranswellR at a concentration of 25 μg/L.In the upper chamber,monocytes were incubated with uPA antibody,uPAR antibody,uPA and Plasminogen Activator Inhibitor(PAI-1) respectively,the number of monocytes moved through TranswellR mambrane were calculated to detect their effect on cell migration. Results uPA had a trend to promote monocytic migration,the number of migrated cells was increased from 179.40±38.49 of the control to 251.00±26.11,P=0.076.PAI-1 and uPA antibody had no effect on cell migration,however the amino terminal fragment of uPA(ATF)significantly suppressed the cells to migrate through transwell,from 179.40±38.49 of the control to 56.40±76.98,p<0.05.Similar result was observed in uPAR antibody,the number of migrated monocytes was decreased from 228.40±83.96 to 151.20±20.33,when the concentration of uPAR rised from 10 μg/L to 160 μg/L,p<0.05. Conclusions uPAR,a membrane protein,participated in monocytic migration induced by MCP-1.The suppressive effect of ATF,which was stronger than that of anti-uPAR antibody,indicated that a specific uPA-uPAR interaction may play an important role in monocytic migration.