Six hundred 'normal' volunteers have been examined, ranging in age from neonates of three days to adults of 65 years. Average compliance was measured for the aortic, iliac, and leg arterial pathways using a non-invasive atraumatic Doppler ultrasound method in non-sedated subjects. No variation of compliance with mean blood pressure was found but there was a strong dependence on age and sex. At birth, leg arteries appear to be markedly more compliant than the aorta. Relative values are reversed in the first five years, after which the aorta remains more compliant, reaching a maximum value around 10 years and then decreasing sharply towards leg values until 20 years. Beyond this age aortic compliance very slowly, and aorta, iliac, and leg arteries appear to tend towards equal compliance in the sixth decade. An explanation for the significant differences between aortic compliance in males and females from menarchy to menopause is offered and implications of these compliance variations in atherogenesis are discussed.