Bilirubin has antioxidant properties and is known to have a role in the prevention of cardiovascular disease. Bilirubin is known to be negatively associated with serum parameters related to atherosclerosis. Triglyceride-rich lipoprotein is known to play an important role in the progression of atherosclerosis. The aim of the present study was to elucidate the relationship between serum bilirubin and serum remnant lipoprotein cholesterol (RLP-c).We examined 270 Japanese males (mean age 64.8 years) without liver dysfunction and anemia from the Outpatient Clinic of Kinki University Hospital. Serum bilirubin, cholesterol, LDL cholesterol, HDL cholesterol, triglyceride and RLP-c levels were measured.Serum RLP-c level was significantly lower in patients in the high bilirubin group than those in the low bilirubin group.The findings of this study show that serum bilirubin within physiological levels may affect the serum RLP-c and suggest bilirubin may have a role in preventing atherosclerosis.