Objective  To investigate the effects of celastrol on the expressions of macrophage migration inhibitory factor (MIF) and matrix metalloproteinase-9 (MMP-9) in the aorta of apoE gene knockout mice with earlier atherosclerosis.   Methods  Eight-week-old ApoE gene knockout male mice were divided randomly into control group and celastrol treatment group (n=6 in each group). The mice in celastrol group were given. celastrol (2 mg·kg

-1

·d

-1

) by intraperitoneal injection for 4 weeks; an

d the mice in control group were only given equivalent amount of dimethyl sulfoxide (DMSO). HE staining of root aorta were used to observe the histomorphological changes and measure the size of plaque in ApoE

-/-

mice. The expressions of MIF and MMP-9 were detected by immunological histochemical method.   Results  The area of lipid plaque in the mice treated with celastrol was significantly smaller than that of the control (P0.01)

and so was the plaque area/aorta cross section area (P0.01). The expression of MIF was significantly decreased in celastrol group compared with the control group (P0.01) The expression of  MMP-9 was also significantly decreased in celastrol group compared with the control group (P0.01).   Conclusion  Celastrol can inhibit the progress of atherosclerotic plaque in ApoE

-/-

mice

which might be relative to its inhibitory effects on the expression of MIF and MMP-9 in the aorta.