The aim of this study is to evaluate the expression of some adhesion molecules on the surface of endothelial cells cultured in contact with knitted Dacron. These molecules, as mediators of cell adhesion, could play a role in the modulation of adhesion on the biomaterials, therefore conditioning the response of tissues to implant. Twenty different cultures of human umbilical vein endothelial cells (HUVECs) were cultured in contact with knitted Dacron. Both HUVECs grown without the material and HUVECs incubated with endotoxin were used as control. After 24 h, the cell adhesion molecules PECAM-1, ELAM-1, ICAM-1 and VCAM-1 were evaluated on the cells by monoclonal antibodies and flow cytometry. After 24 h of contact with knitted Dacron, a significant decrease in the proportion of cells expressing PECAM-1 was observed, as well as a significant increase in the proportion of cells expressing ELAM-1. The contact with knitted Dacron did not induce significant variations of ICAM-1 and VACM-1. The incubation with endotoxin determined a significant increase in the proportion of ELAM-1-positive cells, a significant increase in ICAM-1 fluorescence intensity, and a significant increase both in fluorescence intensity and in the proportion of VCAM-1-positive cells. The results obtained with the endotoxin are in agreement with those reported in the literature. The ELAM-1 increase, observed after contact with knitted Dacron, could favour leucocyte adhesion, while the decrease in PECAM-1 expression could result from an inhibiting effect on the endothelial cell adhesion so as to hinder the mechanisms involved in the endothelialization of the material. The variations were interpreted as inhibiting endothelialization and favouring the leucocyte adhesion effect by knitted Dacron.