['To assess whether a single nucleotide polymorphism (SNP50) of the aromatase gene (CYP19) is associated with polycystic ovary syndrome (PCOS) phenotypes and to investigate the influence of this polymorphism on the response of PCOS to treatment with oral contraceptive pills (OCP).', '162 hirsute women were stratified into a classic PCOS group (hyperandrogenism, ovulatory dysfunction, c-PCOS) and an ovulatory PCOS group (hyperandrogenism, ovulatory cycles, polycystic ovaries, ov-PCOS). 51 women completed a 6-month OCP trial (20 µg ethinyl estradiol + 75 µg gestodene, 21/28 days per cycle, plus 100 mg spironolactone in 32 women with moderate to severe hirsutism). We considered the presence of the polymorphic allele A (AG+AA) in comparison to the absence of the polymorphism (GG) to express results and to perform the comparisons regarding clinical variables.', "Mean age was 23.3 ± 6.9 years. Hirsutism score was similar in c-PCOS and ov-PCOS (15 (11-20) vs. 13 (11-20)). The differences in hormone and metabolic variables between phenotypes were independent of the presence of allele A. In the OCP trial subsample, no differences were observed between genotypes after 6 months' treatment."] Does aromatase gene polymorphism influence clinical phenotype and response to oral contraceptive pills in polycystic ovary syndrome women?