Intelligence quotient (IQ) is the most widely used phenotype to characterize human cognitive abilities. Recent advances in studies on human intelligence have identified many new susceptibility genes. However, the genetic mechanisms involved in IQ score and the relationship between IQ score and the risk of mental disorders have won little attention. To address the genetic complexity of IQ score, we have developed IQdb (http://IQdb.cbi.pku.edu.cn), a publicly available database for exploring IQ-associated human genes. In total, we collected 158 experimental verified genes from literature as a core dataset in IQdb. In addition, 46 genomic regions related to IQ score have been curated from literature. Based on the core dataset and 46 confirmed linked genomic regions, more than 6932 potential IQ-related genes are expanded using data of protein-protein interactions. A systematic gene ranking approach was applied to all the collected and expanded genes to represent the relative importance of all the 7090 genes in IQdb. Our further systematic pathway analysis reveals that IQ-associated genes are significantly enriched in multiple signal events, especially related to cognitive systems. Of the 158 genes in the core dataset, 81 are involved in various psychotic and mental disorders. This comprehensive gene resource illustrates the importance of IQdb to our understanding on human intelligence, and highlights the utility of IQdb for elucidating the functions of IQ-associated genes and the cross-talk mechanisms among cognition-related pathways in some mental disorders for community. © The Author(s) 2013. Published by Oxford University Press.