In this article, we provide an update on the various approaches to "blood compatibilization", and include both passive and active approaches to compatibilizing biomaterials in contact with blood. Broadly speaking, the surface modification approaches involved either repel platelets or attract endothelial cells. For platelet-repelling surfaces, heparin immobilization seems to be the most successful approach. At least two such surfaces have been approved by the health authorities in various countries for applications involving short-term contact with blood. For active endothelialization, ex vivo seeding with autologous cells has been translated into the clinic, while selective endothelial cell capture is a promising approach. In spite of over 30 years of research in this area, a truly intrinsically non-clotting surface has not been developed yet; certain promising avenues have been indicated by the research, which we will critically assess here.