Because apoptosis of inflammatory cells plays a key role in atherosclerosis we sought to determine the role of Fas in the development of atherosclerosis by repopulating the bone marrow cells of atherosclerosis-prone low density lipoprotein receptor null (LDL-R-/-) mice with either cells from lpr mice (lpr-BMT) that have defective Fas expression or from control mice (WT-BMT). This evidence concerns the gene FAS and atherosclerosis.