Structural and functional changes in wall and endothelial components of arterial blood vessels underlie the accelerated vascular disease progression in systemic lupus erythematosus (SLE). Using pulse contour analysis we sought to determine if subclinical vascular abnormalities could be identified in a well-characterised cohort of patients with SLE who had no increase in traditional cardiovascular risk factors. Radial artery pressure waveforms were obtained by applanation tonometry and pressure envelopes were analysed by descriptive and model-based approaches. Waveshape morphology was quantified by a novel eigenvector approach and model-based compliance indices of the large arteries (C1, capacitative arterial compliance) and small arteries (C2, reflective arterial compliance) were derived using a third-order four-element modified Windkessel model. Data were recorded from 30 patients with SLE (mean age 44 +/- 7 years and mean SLAM-R 10 +/- 4) and 19 age-matched control subjects. Significant differences in the lower frequency sinusoidal components of the pressure waveforms were evident between groups (P < 0.05). Both C1 and C2 were significantly reduced in patients with SLE: C1 mean +/- SD 13.5 +/- 4.0 ml/mmHg x 10 versus C1 17.5 +/- 4.8 ml/mmHg x 10 (P = 0.003 in patients vs. controls, respectively) and C2 5.2 +/- 3.4 ml/mmHg x 100 versus C2 9.4 +/- 2.8 ml/mmHg x 100 (P < 0.001 in patients vs. controls, respectively). In this group of SLE patients, without an excess of traditional cardiovascular risk factors and SLAM-R scores indicating mild disease, descriptive and model-based analysis of arterial waveforms identified vascular abnormalities at a preclinical stage.