Polycystic ovary syndrome (PCOS) is the most common endocrine disorders among women in reproductive age, but diagnostic criteria used in clinical practice are still controversial. In 1990 the National Institute of HEALTH (NIH) conference on PCOS recommended that diagnostic criteria should include biochemical evidence of hyperandrogenism and ovarian dysfunction (in the absence of non-classical adrenal hyperplasia) without considering the morphological diagnosis of polycystic ovary by ultrasound as an essential part of the diagnosis. In the Rotterdam PCOS workshop of May 2003, however, PCOS is diagnosed when 2 of the following criteria are recognized: oligomenorrhea and/or anovulation, clinical or biochemical signs of hyperandrogenism, ultrasound findings of polycystic ovary. Further-more, it is underlined that the metabolic study is not necessary for PCOS diagnosis, while it is suggested for "at risk patients" (obesity, diabetes, familiar and obstetrical history) with an oral glucose tolerance test (OGTT). A recent study carried out by our group underlined the role of ultrasound parameter, in particular suggesting a ratio between ovarian stroma area and total area of the ovarian section (S/A), with a cut-off of 0.34, as "gold parameter" for PCOS diagnosis, because it shows high sensitivity and specificity (96.3%, 97.0% for the S/A).