Objective To explore the effect of oxidized low-density lipoprotein (ox-LDL) on Notch 1 expression and cytokine secretion in human acute monocytic leukemia cell line THP1, so as to discuss the role of ox-LDL in atherosclerosis (AS). Methods THP1 cells were stimulated with PMA to induce human macrophages, which were then exposed to ox-LDL of different concentrations. The morphological changes of the cells was observed by phase contrast microscope. The expression of Notch1 mRNA was examined by real-time quantitative PCR (RT-PCR) and protein expression was measured by Western blotting analysis in the cells.The levels of vascular cell adhesive molecule-1(VCAM-1) and monocyte chemoattractant protein-1(MCP-1) in supernatants were determined by ELISA. Results The macrophages differentiated into dendritic like cells 48 h after ox-LDL treatment. Ox-LDL treatment increased Notch1 mRNA and protein expression compared with the control group. Ox-LDL also significantly increased the levels of VCAM-1 and MCP-1 in the supernatant in a dose-dependent manner(P<0.05). The best effect of ox-LDL was seen at the concentration of 50 mg/L. Conclusion Ox-LDL stimulation can increase Notch 1 expression in THP1 cells; meanwhile, it can also promote the secretion of AS-related cytokines. The role of ox-LDL in AS might be partly mediated by Notch1.