Aim The purpose of the present work was to study the inhibitory effect of a triple helix forming oligonucleotides (TFO) on expression of tissue factor (TF) gene in endothelial cells. Methods Antiparallel oligonucleotides T21GTa sequence targeted to shear stress responese element in promoter of TF gene were designed and synthesized by phosphoramidite method and decorated with all PS alinkage. The affinity of TFO and TFO ps were determined by electrophoretic mobility shift assays. Cellular uptake of γ 32 P labelled TFO ps and the effect of TFO ps on expression of TF gene were observed in ECV304 endothelial cell strain. Results TFO ps (T21GTa ps) formed a triplex binding in antiparallel orientation to the puring rich target strand SSRE, with the Kd 3.6×10 10 mol/L. In endothelial cell strand ECV304 the celluar uptake rate of TFO ps (T21GTa ps) is about 11.65%, mainly localized within the nucleus sediment (77.25%),significantly lower the mRNA expression of and the protein synthesis of TF gene, strikingly decreased the coagulation activity of TF. Conclusions TFO ps(T21GTa ps) have significantly inhibited expression of TF gene in endothelial cell.