The relationship between Body Mass Index (BMI) and blood pressure, serum lipids and lipoproteins was studied in 1062 young Japanese women aged 20-39 years. The data was adjusted for age, cigarette smoking and alcohol intake. Subjects were divided into three groups by BMI : a Low group (BMI<19.9), a Middle group (19.9≤BMI <21.9), and a High group (BMI≥21.9) . High group had significantly higher mean value of systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), triglycerides (TG) and low density lipoprotein cholesterol (LDL-C), and the ratio of TC to high density lipoprotein cholesterol (TC/ HDL-C) than Middle group and Low group. High group had significantly lower mean value of HDL-C than Middle group and Low group. The present study shows that there was a higher risk of blood pressure, serum lipids and lipoproteins in high BMI group in young Japanese women aged 20-39 years.