Microparticles (MPs) are membrane vesicles of 0.1 to 1μm diameter generated by budding or shedding from the plasma membrane and released by any cell type into the vascular compartment during activation or apoptosis (Théry et al., 2009). Membrane lineage markers of their originating cell permit to distinguish several circulating MPs, such as platelet-derived MPs (PMPs) or endothelial cell-derived MPs (EMPs). Microparticles are involved in inflammatory and auto-immune diseases, as well as in cardiovascular disorders and the metabolic syndrome (Helal et al., 2010; Leroyer et al., 2010). MP implication in psoriasis pathophysiology is suggested by several features:(i) the pathogenic role of TNF-α (Nestle et al., 2009), a powerful in vitro inducer of EMP generation (Combes et al., 1999);(ii) the presence of activated endothelial cells within cutaneous lesions (Nestle et al., 2009) and EMP generation that may reflect endothelium aggression; and (iii) the presence of platelet activation in psoriasis (Garbaraviciene et al., 2010; Tamagawa-Mineoka et al., 2010) that may generate PMPs (Italiano et al., 2010). Moreover, the association between psoriasis and atherosclerotic risk factors (Boehncke et al., 2010) may be related to excessive MP production. Based on this, we investigated circulating MPs in psoriatic patients.