Soluble endothelial leucocyte adhesion molecule-1 (ELAM-1) has been shown to act as a neutrophil chemoattractant and may also represent a specific marker of endothelial cell damage or activation. Nine patients with anti-neutrophil cytoplasmic antibody (ANCA)-positive vasculitis (p-ANCA: n = 4, c-ANCA: n = 5) were prospectively monitored for disease activity by serial serum ELAM-1, C-reactive proteins (CRPs), von Willebrand factor (vWF) and ANCA levels. Six patients presented acutely with biopsy-proven renal vasculitis. One patient on dialysis, one in remission with stable renal function and one renal transplant patient developed clinical and serological relapse. Seven patients had abnormally high ELAM-1 (>60 ng/ml) levels at presentation. These fell within normal limits a week following pulse methyl prednisolone therapy. This preceded a fall in CRP, vWF and subsequent clinical remission. p-ANCA serology remained positive in 3 cases. One patient relapsed with rising ELAM-1 levels. Two patients developed erroneously positive ANCA serology but serum ELAM-1 remained normal. Six patients with chronic renal impairment of non-vasculitic origin who presented acutely with septicaemia had normal serum ELAM-1 levels (mean +/- SD: 31 +/- 10 ng/ml) at presentation and during the subsequent clinical course. These preliminary findings are encouraging, especially when ELAM-1 is combined with ANCA monitoring in vasculitis. However, further data from larger controlled studies are needed to validate the utility of ELAM-1 in the monitoring of patients with vasculitis.