Background : Oxidative stress plays a major role in atherosclerosis process initiation and increase the risk of cardiovascular disease. Soy milk is one of antioxidant plant source which is able to inhibit atherosclerosis process. The purpose of this study is to investigate the effects of soy milk as an antioxidant through parameters that represent lipid profile such as Triglyceride (TG), High-density Lipoprotein (HDL), and Low-density Lipoprotein (LDL). Oxidant status is represented by Glutathione (GSH), Malondialdehyde (MDA), and Superoxide Dismutase (SOD). Histopathological images of aorta are examined for Perivascular Adipose Tissue (PVAT), foam cell, and lumen diameter. By measuring the parameters, a decrease in oxidative stress will be observed in hypercholesterolemic rats. Materials and Methods : A total of 25 rats were used in the true laboratory experiment which were divided into 5 groups (n=5) using posttest only design. There were a normal diet group, a hypercholesterol diet group, and another 3 groups that were given a hypercholesterol diet with soy milk doses variation of 0.81, 1.62 and 3.24 g/3ml respectively. Rats were treated simultaneously for 90 days. At the end of study rats were sacrificed using chloroform. Then, tissue samples were surgically removed from rat’s aorta and blood was taken by cardiac puncture. The aortic tissue utilized to observe PVAT thickness, lumen diameter, and subendothelial foam cell expression alteration under microscope. Meanwhile, serum from blood sample is used to investigate rats lipid level (TG, HDL, and LDL), and oxidant status (MDA, SOD, and GSH). Lipid profile was measured using Cobas Mira. Oxidant status was read by a spectrophotometer, and histopatological images aorta were placed on a glass slide and stained with Hematoxylin Eosin (HE). Results: ANOVA test showed that soy milk variation dose were significantly (P <0.05) reduce LDL, TG, MDA, foam cells, and increase HDL. Meanwhile, GSH, SOD, PVAT, and Lumen Diameter were less significant, but showing a satisfying improvement trend. Conclusions: Providing antioxidant of soy milk with a certain dose is able to inhibit oxidative stress against atherogenesis in hypercholesterolemic rat.