This study investigates copper (Cu) levels and vascular dysfunction in lean women with polycystic ovary syndrome (PCOS). 44 subjects with PCOS, diagnosed according to Rotterdam criteria, and 42 healthy subjects matched for body mass index and age. Comparison of serum Cu, homocysteine, carotid intima-media thickness (CIMT), brachial artery flow mediated dilation (FMD) was carried out between PCOS patients and the control group. Clinical study was done in Namik Kemal University School of Medicine. The CIMT and concentration of Cu in PCOS patients was significantly higher than the healthy controls. FMD levels in PCOS patients were significantly lower than those in controls. In PCOS patients, CIMT was correlated with estrogen and Cu levels. However, FMD was correlated with age and Cu levels. Among these contributing factors, Cu levels were correlated with a change in CIMT and FMD. CIMT and FMD in PCOS patients were related to Cu levels as well as several cardiovascular risk factors. Thus, increased Cu levels may be responsible for the increased risk of early vascular disease in women with PCOS.