Systemic lupus erythematosus (SLE) is a systemic autoimmune disease in which the underlying pathology is immune complex-mediated vasculitis and its etiology and pathogenesis have not been elucidated. The relationship between the plasma levels of vascular pseudohemophilic factor (vWF) and endothelin (ET) and the degree of disease activity was found to be significantly higher in SLE patients and correlated with the severity of the disease. This may be due to the deposition of anti-DNA antibodies on endothelial cells or the release of immune complexes and IgM anti-endothelial cell antibodies that bind to endothelial cells. It may also be due to the altered vasculitis in SLE patients that affects the microcirculatory function resulting in tissue ischemia and hypoxia and increased synthesis and release of ET due to vascular endothelial cell damage. The increased levels of vWF and ET due to vascular endothelial dysfunction may be involved in the pathogenesis of SLE, but the mechanism of the role of vWF and ET in the pathogenesis of SLE needs to be further investigated. It is suggested that the disease may be effectively controlled if drugs that improve vascular endothelial cell function and antagonize ET are given along with conventional treatment. Ah!