Polycystic ovary syndrome (PCOS) is typically characterized by oligo or anovulation, hyperandrogenism and polycystic ovarian morphology, affecting 5-20% of women of reproductive age [1]. It has drawn significant attention as a major cause of anovulatory infertility and the syndrome of metabolic, reproductive and obstetrical disorders [2 ,+]. Due to heterogeneous clinical features and unclear pathogenesis of PCOS, the diagnosis and treatment strategies remain a matter of debate. To better understand the complex follicular development environment in PCOS, we conducted a TMT-based quantitative proteomic study to compare the composition of proteins, pathways and molecular functions of FF from lean and overweight/obese women with PCOS and that of healthy controls.