Aim To study the effects of oxidized high density lipoprotein (ox HDL) on the migration of THP 1 cells and monocyte chemoattractant protein 1 (MCP 1)in the conditioned medium. Methods Human plasma lipoproteins were separated by one step ultracentrifugation with a simple density gradient, the in vitro oxidation of high density lipoprotein (HDL) was mediated by CuSO 4. THP 1 cells (a human acute monocytic leukemia cell line) were cultured for the experiments. The migration of THP 1 cells stimulated by oxidized high density lipoprotein was assayed with reformed Boyden. Results The migrated cells in the membrane (in Boyden well) were 52.5±6.5 in control group, 93.5±10.1 in 50 mg protein/L oxidized high density lipoprotein group(p<0.05), 148.5±21.6 in 100 mg protein/L oxidized high density lipoprotein group(p<0.01), 112.8±19.9 in oxidized high density lipoprotein+E 2 (17 β estradiol) group(p<0.05, compared with 100 mg protein/L oxidized high density lipoprotein group), and without significant changes in HDL groups. MCP 1 in the conditioned medium of THP 1 cells were as follows: 76.5±11.6 ng/g protein in control group, 141.0±19.5 ng/g protein in 100 mg protein/L oxidized high density lipoprotein group(p<0.01), 117.5±15.2 ng/g protein in oxidized high density lipoprotein+E 2 group(p<0.05 compared with oxidized high density lipoprotein group), and without significant change in HDL group. Conclusions oxidized high density lipoprotein could stimulate the migration of THP 1 cells and the production of MCP 1. It suggested that oxidized high density lipoprotein may participate in the primary pathogenesis of atherosclerosis by promoting the migration of monocyte to the intima of artery and increasing MCP 1; 17 β estradiol may have protective effect.