This study aimed to reveal if peptide profiling of individual human follicular fluid could become a new non-invasive predictive biomarker for oocyte quality, and attempted to discover candidate biomarkers for fertilization. In biomarker studies, because of normal clinical or biological variabil-ity, candidate biomarkers need to be validated across a large number of samples. To ensure that the discovered biomarkers are truly associated with oocytes quality and fertilization rather than the result of variability, three independent experiments were designed with a large population. In the present study, we investigated the peptide profile of human follicular fluid with fertilized and non-fertilized oocytes from patients undergoing in vitro fertilization using proteomic analysis with liquid chromatography-tandem mass spectrometry. We additionally determined the protein identi-ties of the discovered peptide biomarkers as a first step toward understanding the pathways in which they may function.