Aim To observe the effects of Chlamydia pneumoniae infection on migration of endothelial cells,to investigate the interventive effect of Berberine on Chlamydia pneumoniae induced-endothelial cell migration and to explore its possible mechanism. Methods Endothelial cells pretreated with Berberine at different concentration(0,100,150 and 200 mmol/L) were infected by Chlamydia pneumoniae AR-39 in vitro.At 24,48 and 72 h after Chlamydia pneumoniae infection,the wound healing assay and Transwell assay were performed to observe the effects of Berberine on migration of endothelial cells.The mRNA expression and enzymatic activity of PI3K were detected by RT-PCR and ELISA at the corresponding time point. Results Migration of endothelial cells,the mRNA expression and enzymatic activity of PI3K increased significantly at 24,48 and 72 h after Chlamydia pneumoniae infection in comparison with the control group(P<0.01).Migration of endothelial cells,the mRNA expression and enzymatic activity of PI3K decreased markedly after administration of the PI3K inhibitor of LY294002 compared with the Chlamydia pneumoniae infection group(P<0.01).Migration of endothelial cells,the mRNA expression and enzymatic activity of PI3K decreased markedly after administration of the middle-dose and high-dose Berberine compared with the Chlamydia pneumoniae infection group(P<0.01),and migration of endothelial cells was positively correlated with the mRNA expression(r1) and enzymatic activity of PI3K(r2)(r1=0.841,r2=0.832,P<0.01). Conclusions Chlamydia pneumoniae may induce endothelial cell migration via the activation of PI3K.Berberine can antagonize Chlamydia pneumoniae induced-endothelial cell migration possibly through down-regulating the PI3K mRNA expression and inhibiting the activation of PI3K.