1. Information on the interaction between mechanical strain and the elastic properties of large arteries could give insight to the origin of haemodynamic vascular injury, possibly resulting in formation of atherosclerotic plaques. Intra-individual variation in the elastic properties of muscular arteries measured using non-invasive techniques has been observed. This variation could be due to changes in blood pressure, since the elastic properties of muscular arteries are strongly non-linear. 2. The objective of the present study was to evaluate variability in the elastic properties of a muscular artery over a time period of up to 1 h. Furthermore, the relation between changes in elastic properties and alterations in blood pressure was studied. With a non-invasive high-resolution ultrasound technique, the diameter and distension of the femoral artery were assessed by repeated measurements in 10 healthy subjects (mean age 27 +/- 2.9 years) under resting conditions over 40-60 min. Intra-arterial blood pressure of the contralateral common femoral artery and heart rate were recorded simultaneously. From the distension and pulse pressure, the distension/pressure ratio was calculated, a measure of the compliance. For each parameter the variation coefficient was computed. 3. In all subjects a considerable variation was found in distension (mean variation coefficient 14.8%) but not in pulse pressure (mean variation coefficient 3.7%). The expected positive correlation between pulse pressure and distension was absent in eight subjects. As a consequence, large intra-individual variation was found in the distension/pressure ratio (mean variation coefficient 15.3%).(ABSTRACT TRUNCATED AT 250 WORDS)