An endovascular graft, having both an expandable stent portion and a stent cover portion positioned, the graft itself and/or a stent cover-portion coated with a bioactive agent adapted to promote initial thrombus formation, preferably followed by long term fibrous tissue ingrowth. The endovascular graft prevents endoleaking by promoting a short term hemostatic effect in the perigraft region. This short term effect can, in turn, be used to promote or permit long term fibrous tissue ingrowth. Particularly where the stent cover portion is prepared from a porous material selected from PET and ePTFE, the bioactive agent can include a thrombogenic agent such as collagen covalently attached in the form of a thin, conformal coating on at least the outer surface of the stent cover. An optimal coating of this type is formed by the activation of photoreactive groups.