Clinical manifestations of vasculitis, as a complication of rheumatoid arthritis (RA), can be postulated as a consequence of immune response abnormalities and endothelial cell dysfunction. In this study we searched for the relationship between the extent of vascular involvement and either serum sICAM-1 or selenium concentrations. We also explored the possible interaction of serum selenium with sICAM-1 to provide a greater understanding of their role in rheumatoid vasculitis (RV). For the study, we measured the serum titers of sICAM-1 using an ELISA assay and the serum selenium concentrations using the ETAAS method in 37 women suffering from RA and 18 normal women serving as controls. All the RA patients were evaluated by extensive clinical, laboratory and capillaroscopic studies. In all patients with extra-articular manifestations, severe or moderate changes in nailfold capillaroscopy were found. Serum sICAM-1 titers in RA patients with mild vasculitis on nailfold capillaroscopy did not differ significantly from those of the healthy subjects, whereas a higher sICAM-1 level seemed to reflect the more intensive vascular changes in capillaroscopy. These data suggest that sICAM-1 serum levels may reflect the extent of the microvascular involvement in RA patients. Compared with controls, all the RA patients had markedly lower serum selenium concentrations, irrespective of the degree of the capillaroscopic vascular changes. A significant inverse correlation between sICAM-1 and selenium was found in the controls (r = -0.54; P<0.02). By contrast, no correlation was noted in RA patients (r=0.10, P not significant). This suggests that the sICAM-1 shedding in RV does not appear to be influenced by selenium, presumably owing to its low serum concentration.