Abstract: AIM:To investigate whether orphan receptor Nur77 is involved in the formation of vulnerable carotid atherosclerotic plaque in ApoE-/- mice. METHODS: Using the method of partial ligation of left carotid and left renal arteries, we generated an ApoE-/- mouse model of vulnerable carotid atherosclerotic plaque. The pathological changes of atherosclerotic plaques were observed using H/E staining and the expression of Nur77 was detected by laser confocal microscopy after immunofluorescence staining. Macrophages (murine RAW 264.7 cells) were cultured and were stimulated with oxLDL and its main lipid components 7-ketocholesterol (7-KC) or free cholesterol (FC) and some inflammatory mediators (LPS or IL-1β). The protein expression of Nur77 was detected by Western blotting. RESULTS: Nur77 is highly expressed in vulnerable carotid atherosclerotic plaques in ApoE-/- mice. In addition, oxLDL and its main lipid components (7-KC or FC) and some inflammatory mediators (LPS or IL-1β) induced the expression of Nur77 in murine RAW 264.7 cells in vitro. CONCLUSION: Orphan receptor Nur77 participates in the formation of vulnerable carotid atherosclerotic plaque in ApoE-/- mice.