To explore the effects of different doses of puerarin on proliferation of cultured vascular endothelial cells in vitro. The hearts of three new-born SD rats 5 days old were mechanically minced and enzymatically digested with collagenase and trypsin, then vascular endothelial cells were counted, washed and resuspended in Dulbecco's minimum essential medium (DMEM) added with 20% heat inactivated fetal calf serum, then inoculated in 2% gelatin-coated tissue culture flasks. Vascular endothelial cells at passage 3 were used in the experiment. Except for the normal control group, the vascular endothelial cells were cultured with puerarin in various concentrations (0.01, 0.1, 1, 10 and 100 micromol/L) for 24 hours, and the morphology and the number of the cultured endothelial cells were observed. Methyl thiazolyl tetrazolium (MTT) colorimetry was used to determine the proliferation of the cultured vascular endothelial cells. Flow cytometry (FCM) were used to detect the proliferation index (PI) of the vascular endothelial cells and the expression of proliferating cell nuclear antigen (PCNA) was detected by immunohistochemical method. The cell morphology was normal under the inverted microscope in each group. The number and proliferation activities of vascular endothelial cells were significantly increased by 1, 10 and 100 micromol/L puerarin compared with those of the blank control group, especially the 100 micromol/L puerarin group, and there were no remarkable changes in with 0.1 micromol/L and 0.01 micromol/L puerarin groups. The same results were seen in the positive rate of PCNA expression and PI. Puerarin has dose-dependent effects on the proliferation activity of vascular endothelial cells.