Psoriasis is an inflammatory, immunomediated skin disorder associated with an increased risk of cardiovascular disease. Psoriasis patients are at higher risk of atherothrombotic disease independently of the concomitance of traditional cardiovascular risk factors. Inflammation is one of the mechanisms involved in the development of endothelial dysfunction (ED), which is a marker of subclinical atherosclerosis. This study was designed to assess ED in psoriasis patients non-invasively. Flow-mediated dilation (FMD) and nitroglycerin-induced dilation (NID) of the brachial artery were measured by ultrasonography in 32 psoriasis patients and 31 healthy controls. Diabetes mellitus, renal failure, a history of neoplasm, major cardiovascular and cerebrovascular disease and psoriatic arthritis were exclusion criteria. Psoriasis patients exhibited a significantly lower percent FMD compared with controls, but not a significantly different NID. Our data confirm that psoriasis is associated with impaired endothelial function and suggest that these patients suffer from subclinical atherosclerosis.