In COPD, the systemic effects of the disease reflect the structural and/or biochemical alterations occurring in the structures or organs other than the lungs in relation to the characteristics of the primary disease. The disorders of endothelial structures due to COPD may lead vascular pathologies, such as ischemic heart disease, stroke, to occur more commonly in those with COPD. On consideration of the fact that the vascular endothelium is a major site in which the systemic effect of the inflammation occurs, should von Willebrand Factor, a clotting factor of endothelium origin, and the plasma level of fibrinogen vary with the severity of the disease in COPD, the variability of arterial blood gas values, and the stability or exacerbation of the disease? Considering the fact that microalbuminuria is an indirect manifestation of the renal endothelial permeability and/or renal perfusion; should there be an association between microalbuminuria and the severity of COPD? Therefore, in order to assess the effect of the systemic inflammation in COPD on the vascular endothelium, we compared the levels of the plasma vWF, fibrinogen, 24-h urine microalbuminuria of those with stable COPD (33 patients) and exacerbation of COPD (26 patients) with those of the controls (16 healthy subjects). The mean age was 63.42 -/+ 10.29, 68.00 -/+ 9.77 and 59.63 -/+ 14.10 years in SCOPD, COPDAE, and CG, respectively. The level of microalbuminuria was found to increase significantly in COPDAE group, compared to that of the controls (P = 0.004). When we investigated the relation between smoking burden and microalbuminuria, vWF, fibrinogen levels, the amount of consumption and positive relationship were found significant. (r = 0.336, P = 0.003 between smoking pack-years and vWF, r = 0.403, P = 0.001 between smoking pack-years and fibrinogen, and r = 0.262, P = 0.02 between smoking pack-years and microalbuminuria). The levels of vWF and fibrinogen are AECOPD > SCOPD > CG, with the highest being in AECOPD, and the difference among the groups was statistically significant. The relationship between the level of hypoxemia and microalbuminuria, fibrinogen and vWF was found to be significant (r = -0.360, P = 0.005 between oxygen saturation and microalbuminuria, r = -0.359, P = 0.005 between the level of PaO(2) and fibrinogen, and r = -0.336, P = 0.009 between PaO(2) and vWF). In conclusion, the levels of plasma vWF, fibrinogen, and microalbuminuria may be helpful in grading the severity of COPD exacerbation. The related increase in these markers may represent a possible pathophysiological mechanism behind the increased vascular morbidity of patients with COPD and detecting indirectly the endothelial dysfunction as a manifestation of systemic outcomes due to COPD and in detecting earlier the cases in which the risk for developing the associated complications are higher. We suggest that further studies are necessary to investigate the impact of antithrombotic treatment on microalbuminuria, plasma vWF and fibrinogen as markers of endothelial dysfunction coexisting COPD exacerbation.