Background: Psoriasis, a common inflammatory disease, is associated with atherosclerotic vascular diseases, including stroke, myocardial infarction, and impaired microcirculations, among which circulating microparticles play an important role. In severe psoriasis, there are increased endothelial- and platelet- microparticles that are reduced by TNF-α blockers in parallel with clinical improvement. However, whether Stelara(ustekinumab) treatment would decrease the level of microparticles remains unknown.