Polycystic ovary syndrome (PCOS) is the most frequent reproductive endocrinopathy in reproductive ages with an incidence of 4-6%. Also, a group of long term health risks such as type 2 diabetes mellitus, endometrial cancer and coronary heart disease should be evaluated associated with underlying pathophysiology of PCOS. However, the selection of the optimum diagnostic criterion to confirm the diagnosis is controversial. From 1990 NIH sponsored consensus to 2003 Rotterdam ESHRE/ASRM sponsored international meeting, an important degree of changes have been considered. In this manuscript, the recent PCOS associated diagnostic criterion, the reasons forcing the authors to alter the diagnostic criterion and long term health risks were reviewed.