Aim: To investigate the effects of CpG-oligodeoxynucleotide (CpG-ODN) on the formation of macrophage foam cells and related gene expression. Methods: A gene expression profile was examined by microarray techniques, and mRNA expression was detected by reverse transcriptase polymerase chain reaction (RT-PCR). The cholesterol and cholesteryl ester contents of cells were determined by high performance liquid chromatography. Results: CD36, LPL, and Fcγ2b, which were related to lipid metabolism and the formation of macrophage foam cells, were upregulated after CpG-ODN stimulation. The mRNA expression related to the formation of foam cells was confirmed by semiquantitative RT-PCR. Moreover, histochemical analysis confirmed that lipid deposits inside cells increased after CpG-ODN treatment. However, using flow cytometry, we found that CpG-ODN had no effect on the expression of membrane receptors. Conclusion: CpG-ODN up-regulated the expression of genes in macrophage foam cell formation. Aim: To investigate the effects of CpG-oligodeoxynucleotide (CpG-ODN) on the formation of macrophage foam cells and related gene expression. Methods: A gene expression profile was examined by microarray techniques, and mRNA expression was detected by reverse transcriptase polymerase chain reaction Results: CD36, LPL, and Fcγ2b, which were related to lipid metabolism and the formation of macrophage foam cells, were upregulated after CpG- ODN stimulation. The mRNA expression related to the formation of foam cells was confirmed by semiquantitative RT-PCR. Moreover, histochemical analysis confirmed that lipid deposits inside cells increased after CpG-ODN treatment. However, using flow cytometry, we found that CpG-ODN had no effect on the expression of membrane receptors. Conclusion: CpG-ODN up-regulated the expression of genes in macrophage foam cell formation.