['Chronic venous insufficiency (CVI) results when the veins in the legs no longer pump blood back to the heart effectively. Microparticles (MPs) are small membrane vesicles released by several circulating and vascular cells upon activation or apoptosis.', 'The purpose of this study was to assess the subpopulations of circulating endothelial (EMPs) and platelet microparticles (PMPs) in CVI, and to disclose their contribution in mediating dysfunction of human peripheral venules.', 'Human peripheral venules were explanted during leg surgery on patients with CVI and on control subjects (C); concurrently, blood samples were collected and circulating MPs isolated. The techniques used were: flow cytometry, fluorescence and electron microscopy, myograph technique and western-blotting technique.', 'The results showed that compared with controls, patients with CVI had: (i) a marked elevation of circulating EMPs and PMPs; (ii) a structural modification of the venous wall consisting of activation of endothelial and smooth muscle cells, an abundance of intermediary filaments and synthesis of hyperplasic-multilayered basal lamina; (iii) a significantly altered reactivity of the venous wall, closely associated with EMPs and PMPs adherence; (iv) altered contractile response to noradrenaline, acetylcholine, 5-hydroxytryptamine and KCl, and an impeded relaxation in response to sodium nitroprusside; and (iv) a substantially increased protein expression of tissue factor (TF) and of P-Selectin both in the venular vascular wall and on the surface of EMPs and PMPs.'] Is chronic venous insufficiency associated with elevated level of circulating microparticles?