A manually curated knowledgebase on polycystic ovary syndrome (PCOS). PCOS-related information available through scientific literature is cross-linked with molecular, biochemical and clinical databases. Information on associated genes, SNPs, diseases, gene ontologies and pathways along with supporting reference literature is collated and integrated in PCOSKB. PCOSKB will be useful for scientists and clinicians. The database currently holds information on 241 genes associated with PCOS.