OBJECTIVE: We aimed to assess plasma Von Willebrand factor (vWF) levels in women with polycystic ovary syndrome (PCOS) and to compare these levels among the different PCOS phenotypes.DESIGN: We studied 140 women with PCOS and 40 age and body mass index (BMI)- matched healthy women (control group).RESULTS: Plasma vWF antigen levels were higher in women with PCOS than in controls (p=0.017). Plasma vWF antigen levels were also higher in patients with phenotypes 1 [i.e. with anovulation (ANOV), biochemical hyperandrogenemia or clinical manifestations of hyperandrogenemia (HA) and polycystic ovaries (PCO)] and 2 (i.e. with ANOV and HA but without PCO) than in controls (p=0.017). In contrast, plasma vWF antigen levels did not differ between controls and patients with phenotypes 3 (i.e. with HA and PCO but without ANOV) and 4 (i.e. with ANOV and PCO but without HA) or between patients with phenotypes 1 and 2 and patients with phenotypes 3 and 4. When overweight/obese and normal weight subjects were analyzed separately, plasma vWF antigen levels did not differ between patients with PCOS (regardless of phenotype) and controls.CONCLUSIONS: Plasma vWF levels are elevated in women with PCOS. This increase appears to be more pronounced in women with phenotypes 1 and 2 of PCOS. Given the association between vWF levels and increased incidence of cardiovascular events, the evaluation of vWF levels in women with PCOS might be helpful for cardiovascular risk stratification, but prospective studies are needed to support this hypothesis.