Polycystic ovary syndrome (PCOS) occurs in 5-10% of premenopausal women. Studies suggest that PCOS is associated with increased risk of coronary heart disease (CHD). To investigate this relationship, 15 PCOS women (group 1) and 10 healthy women (group 2) were studied. Blood leukocyte counts (white blood cells, WBC) and serum levels of total cholesterol, HDL-cholesterol, LDL-cholesterol, sensitive C-reactive protein (sCRP), and neopterin were measured in the 2 groups. There were no significant differences in serum total cholesterol, HDL-cholesterol, or LDL-cholesterol concentrations between groups 1 and 2. Blood WBC counts and serum levels of neopterin and sCRP were significantly higher in group I than group 2. The median (min-max) levels were: WBC, group 1: 8.05 (5.10-9.70) cells x 10(9)/L, group 2: 6.25 (4.70-9.70) cells x 109/L (p < 0.01); neopterin, group 1: 10.6 (7.5-49.5) nmol/L, group 2: 9.6 (6.5-12.9) nmol/L (p < 0.05); and sCRP, group 1: 7.0 (1.2-12.0) mg/L, group 2: 2.0 (0.1-12.0) mg/L (p < 0.01). This study shows that blood WBC counts and serum sCRP and neopterin levels are significantly elevated in women with PCOS. These findings support an increased risk for early-onset cardiovascular disease in women with PCOS. This is the first report that women with PCOS have higher serum neopterin levels than healthy women with regular menstrual cycles.