The coordinate induction of protease activities and cell migration is a principal feature of endothelial cells (ECs) invading the interstitial space in the initial step of angiogenesis. However, the molecular mechanisms of these events are not fully characterized. Ets‐1 is a member of the ets gene family of transcription factors, which binds to the Ets binding motif in the cis‐acting elements and regulates the expression of certain genes. Four typical angiogenic growth factors, aFGF, bFGF, VEGF, and EGF, induced the expression of ets‐1 mRNA in either human umbilical vein endothelial cells (HUVECs), ECV‐304 cells (immortalized HUVECs), or human omental microvascular endothelial cells (HOMECs). The expression of ets‐1 reached its maximum at 2 hr after factor addition and then decreased to the basal level by 12 hr. For characterization of the role of Ets‐1 in angiogenesis, ets‐1 antisense and sense oligodeoxynucleotides (ODNs) were constructed. The ets‐1 antisense ODN but not sense ODN efficiently blocked the synthesis of Ets‐1 protein by human ECs in response to angiogenic growth factors. Moreover, the ets‐1 antisense ODN but not sense ODN almost completely abolished the binding of endothelial cell extract to DNA containing the Ets binding motif. The expression of urokinase‐type plasminogen activator and matrix metalloproteinase‐1 and the migration of ECs in response to growth factors were significantly inhibited by ets‐1 antisense ODN but not by sense ODN. Tube formation by HOMECs in type 1 collagen gel stimulated with EGF was abrogated by ets‐1 antisense ODN. Finally, the expression of Ets‐1 protein in ECs during angiogenesis in vivo was confirmed by an immunohistochemical analysis using a murine angiogenesis model. These results indicate that the induction of ets‐1 mRNA is a mutual phenomenon in ECs stimulated with angiogenic growth factors. Ets‐1 appears to play an important role in angiogenesis, regulating the expression of proteases and the migration of ECs. © 1996 Wiley‐Liss, Inc.