AIM: To purify murine yolk sac endothelial cells (mYS-EC) and investigate the cytokines mRNA expression in mYS-EC. METHODS: The murine yolk sacs were digested with 0.1% collagenase, resuspended in DMEM and counted after digestion and centrifugation. The yolk sac adherent cells were cultured in DMEM containing 15% FBS with 10% mBMEC-CM or 5?g/L VEGF, ECGF and bFGF. The phagocytose function and expression of vWF were evaluated via particle phagocytosis and immunohistochemistry method. Atlas cDNA expression array was used for analysis of cytokine expression in mYS-EC. RESULTS: Colonies consisting of pure yolk sac endothelial cells were obtained in liquid culture system containing 15% FBS and 10% mBMEC-CM or 5?g/L VEGF, ECGF and bFGF. For complete purification of the endothelial cells, subsequent passage was also necessary. Cellular cord formed during passage culture. The endothelial cells were round or oval sharp in morphology, positive in phagocytosis and factor VIII related antigen (von Willebrand's Factor,vWF). The mRNA expressions of cytokines, such as TGF-?2, TNF-?, IFN-?, FL, BMP-4, MIP-1?, BMP-2A, FLT2, endothelin 2, thymosin ?10, IL-6, IL-13, IL-9, SCYA5 and ACBP were detected in mYS-ECs. CONCLUSION: mYS-EC was purified and expanded in vitro . The mRNA expression of 15 kinds of cytokines was detected in mYS-ECs by Atlas arrays.