Since 2004, the Rotterdam criteria have been used in the diagnosis of polycystic ovary syndrome (PCOS), requiring the presence of two of the following three criteria: oligo-/anovulation, hyperandrogenism or polycystic ovaries. Reports of high prevalences of polycystic ovaries in younger women have caused concerns about overdiagnosis. Recently, the international guideline for PCOS has recommended raising the follicle threshold for polycystic ovaries and avoiding ultrasound in adolescents. Anti-Müllerian hormone has been proposed as a substitute marker for polycystic ovaries but is not yet considered adequate for diagnosis.