The association of body fat distribution as measured by the ratio of waist to hip girth (WHR) to age, to serum total cholesterol and HDL-cholesterol and to blood pressure was studied in a population-based sample of 2461 men and 2768 women aged 25 to 64 years not treated with cardiovascular drugs. In men, the relationships of age with WHR and age with body mass index (BMI) were similar, an increase levelling at the age of about 50 years. In women, BMI increased linearly, but WHR exponentially with age. In both sexes, age-adjusted WHR and BMI associated positively with non-HDL cholesterol, and with systolic and diastolic blood pressure, and inversely with HDL-cholesterol and the HDL/non-HDL cholesterol ratio. WHR and BMI were independently related to several cardiovascular risk factors. HDL-cholesterol concentration was 19% lower in men, and 17% lower in women who belonged to the upper tertile of both WHR and BMI, than in the subjects in the lower tertiles of WHR and BMI. Age-adjusted WHR and BMI also predicted fasting and 2-hour post-challenge blood glucose values in women aged 45 to 64 years, but not in men. The WHR provides additional information on elevated cardiovascular risk factors in cross-sectional analysis among middle-aged men and women independently of BMI. The measurement of WHR in large-scale risk factor surveys should be recommended, in order to assess the independent contribution of WHR to the risk of cardiovascular disease, and to find out the importance of WHR for the prevention of chronic diseases.