Recently, we and others demonstrated the unique potential for glycosyl phosphatidylinositol (GPI) anchored proteins to transfer from one cell membrane to another in a process we termed ‘painting’. The GPI-anchored proteins were shown to transfer intact and functional. The full significance of this phenomenon has yet to be fully realized, but implications exist in many areas including disease transmission (prions), cell protection (endothelial cells), and senescence (erythrocytes). It is of interest to note that cells exhibiting limited or no biosynthetic capacity (spermatozoa and erythrocytes) have been implicated thus far in cell-cell transfer of GPI-linked molecules. This observation demonstrates the potential for GPI-linked proteins to be ‘painted’ onto cells which otherwise may be incapable of expressing exogenous proteins. We show in this paper that GPI-linked CD59 and decay-accelerating factor will transfer intact from erythrocytes to endothelial cells in transgenic mice. We also demonstrate that the transfer process occurs under physiological conditions using several experimental models including organ and bone marrow transplantation. We detail the procedure to effect transfer of GPI-linked proteins from one cell type to another in either an in vivo or in vitro system.