Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age in the United States and has been associated with several diseases including cardiovascular disease, obesity, and glucose intolerance. In this study, systolic blood pressure, diastolic blood pressure, pulse pressure (vascular compliance), large artery elasticity, systemic vascular resistance (SVR), total vascular impedance (TVI), and body mass index (BMI) were measured before and after treatment with spironolactone in 10 women with PCOS. Systolic BP, diastolic BP, and BMI were similar prior to treatment and after treatment. Pulse pressure decreased slightly post-treatment compared to pretreatment but not to significance (P = 0.07). The results show that after treatment with spironolactone, there was a statistically significant increase in large artery elasticity (P = 0.047), while there was a statistically significant decrease in SVR and TVI (P = 0.0005 and P = 0.03). This study indicates that treatment with spironolactone improves large artery elasticity and reduces systemic vascular resistance without any change in small artery elasticity.