Women with polycystic ovary syndrome (PCOS) carry a number of cardiovascular risk factors. Cardiovascular morbidity is elevated even in young women with PCOS. Low-grade chronic inflammation, reflected in elevated levels of serum C-reactive protein (CRP) and endothelial dysfunction have recently been linked to development of atherosclerosis. We compared high-sensitivity (hs) CRP concentrations and endothelium dysfunction in 37 women with PCOS and 25 control subjects matched as a group for age and body mass index (BMI). Arterial endothelium and smooth muscle function was measured by examining brachial artery responses to endothelium-dependent and endothelium-independent stimuli.