Slow endothelialization (endothelial lining on the arterial surfaces) on poly(L-lactic acid) (PLLA) materials is one of many concerns limiting its use in the vascular system. Surface coating with extracellular matrix (ECM) proteins is a well described method used for modifying surface properties of biomaterials in order to encourage cell growth. However, optimization of ECM proteins to promote the adhesion and growth of Human Aortic Endothelial Cells (HAEC) has not been well-investigated. In this study, we compared the effect of common ECM proteins such as fibronectin, collagen, laminin, vitronectin, and matrigel on the HAEC adhesion and growth on PLLA materials. It was found that fibronectin not only had the highest cell adhesion and proliferation, but also maintained normal cell morphology and endothelial cell function. Moreover, endothelial cells remained better on this surface under physiological shear stress levels. These results suggested fibronectin is the best ECM protein to promote endothelialization on PLLA materials.