In the past decade, the high morbidity and mortality of atherosclerotic disease have been prevalent worldwide. High-fat food consumption has been suggested to be an overarching factor for atherosclerosis incidence. This study aims to investigate the effects of kefir peptides on high-fat diet (HFD)-induced atherosclerosis in apolipoprotein E knockout (ApoE −/−) mice. 7-week old male ApoE −/− and normal C57BL/6 mice were randomly divided into five groups (n = 8). Atherosclerotic lesion development in ApoE −/− mice was established after fed the HFD for 12 weeks compared to standard chow diet (SCD)-fed C57BL/6 and ApoE −/− control groups. Kefir peptides oral administration significantly improved atherosclerotic lesion development by protecting against endothelial dysfunction, decreasing oxidative stress, reducing aortic lipid deposition, attenuating macrophage accumulation, and suppressing the inflammatory immune response compared with the HFD/ApoE −/− mock group. Moreover, the high dose of kefir peptides substantially inhibited aortic fibrosis and restored the fibrosis in the aorta root close to that observed in the C57BL/6 normal control group. Our findings show, for the first time, anti-atherosclerotic progression via kefir peptides consumption in HFDfed ApoE −/− mice. The profitable effects of kefir peptides provide new perspectives for its use as an antiatherosclerotic agent in the preventive medicine. The World Health Organization (WHO) suggests that cardiovascular diseases (CVDs) are the primary cause of mortality, and considerably more individuals die annually from CVDs than from any other cause globally. Atherosclerosis is known as the major cause of CVDs. The pivotal initiators involved in atherosclerosis development are enhanced levels of low-density lipoprotein (LDL) cholesterol in the circulation, vascular reactive oxygen species (ROS) generation, and inflammation 1. It has been suggested that inflammation plays a fundamental role in CVDs and atherosclerotic lesion progression 2. In early atherosclerotic lesions, the accumulation of foam cells leads to fatty streak formation. Immune cells and vascular smooth muscle cells (VSMCs) accumulate in the subendothelial layer of the artery wall 3,4. Various inflammatory cells, including neutrophils, macrophages, and lymphocytes, are involved in atherosclerosis progression; however, macrophages were reported as the first inflammatory cell associated with atherosclerosis and predominantly present within atherosclerotic vessels 5-7 .