Based on the available data, it is the view of the AES Task Force on the Phenotype of PCOS that there should be acceptance of the original 1990 National Institutes of Health criteria with some modifications, taking into consideration the concerns expressed in the proceedings of the 2003 Rotterdam conference. A principal conclusion was that PCOS should be first considered a disorder of androgen excess or hyperandrogenism, although a minority considered the possibility that there may be forms of PCOS without overt evidence of hyperandrogenism but recognized that more data are required before validating this supposition . Finally, the task force recognized, and fully expects, that the definition of this syndrome will evolve over time to incorporate new research findings.