The systolic ankle and arm blood pressure has been measured by Doppler ultrasound technique in 666 men and women aged 60 yr. The Doppler method was found suitable for use in a population survey as the cost is low, the measurements are rapid, painless and can be well standardized. The reproducibility was 2.9 mm Hg, measured as the mean standard deviation of 10 measurements in ten persons. Decreased ankle blood pressure was defined as a ratio between the systolic ankle pressure and the arm pressure of less than 90% in at least one of the four leg arteries examined. Decreased ankle pressure in one or more arteries was present in 16% of the men and 13% of the women. The prevalence of intermittent claudication was 5.8% in men and 1.3% in women. Pulselessness in one or two of the arteries of the foot occurred in 11.9% of the men and 8.8% of the women. According to all three criteria 2.3% of the population were abnormal, 3.3% of the men and 1.0% of the women. 82% had no signs of arteriostenosis. The normal individuals had on an average ankle/arm blood pressure indices higher than 100%. The ankle/ arm indices were related to other signs of arteriosclerosis: Angina pectoris, dyspnoea on effort and ECG signs of ischemia. The findings have been used in an evaluation of the risk factors for peripheral arteriosclerosis. The values, at age 50, of blood pressure, serum cholesterol, serum triglyceride, smoking habits, heart rate and male sex were significantly associated with signs of peripheral arteriostenosis and with the ankle/arm index at age 60.