In this study, we demonstrated that Kiom-18, a novel composition of C. cassia, P. densiflora, C. longa and G. glabra, prevents atherosclerosis through the anti-proliferative effect on VSMCs via the regulation of cell cycle-related proteins such as CDK2, CDK4, cyclin D1, cyclin E1, Rb, and PCNA. Here, CDK4 is linked to atherosclerosis.