This study was designed to investigate the influence of natural brown and black rice consumption on plasma lipid parameters, transit time, and thickness of the aortic wall in rats fed different combinations of grains. Fifty male rats were divided into five groups and raised for eight weeks with diets containing white rice (WR), white rice and brown rice (WRBR), white rice and black rice (WRBL), brown rice and black rice (BRBL), or wheat flour (WH). Gut transit time was the shortest in the BRBL group, and was longer in the order of WRBL, WRBR, WR, and WH group. Plasma lipid profiles differed significantly according to the grain combination. The BRBL group had the lowest levels of triglyceride (TG), total cholesterol (T-C), and low-density lipoprotein cholesterol (LDL-C), and the highest plasma high-density lipoprotein cholesterol (HDL-C) concentration among all groups. The aortic wall thickness hatro for body weight was lower in rats in order of BRBL, WRBR, WH, WRBL, and WR group. In conclusion, black rice and brown rice have anti-atherogenic effects by decreasing plasma lipide profiles and attenuating the thickness of the aortic wall.