To research the inhibitive effect and mechanism of baicalin on apoptosis of vascular endothelial cells in rats induced by oxidized low density lipoprotein(ox-LDL).Methods:The rats were firstly intravenously injected with LDL, then intervened by baicalin to be observed for any changes, and compared with rats treated with NaCl2 only, and rats treated with LDL but without baicalin intervention. Apoptosis were detected by TUNEL method, activity of caspase-3 enzyme was assayed by colorimetric assay.Results:Compared with NaCl2 only rats, the LDL group showed larger number of apoptosis cells, and caspase-3 with higher activity (P<0.01) which were inhibited significantly by baicalin as shown in the intervention group (P<0.01).Conclusion:LDL stimulates activity of caspase-3 to cause apoptosis of vascular endothelial cells; baicalin can inhibit such apopotosis by restricting activity of caspase-3.