Abstract: In recent years, gene trapping mediated by T-DNA has provided a pow erful tool to isolate and identify genes. As the sequencing of the Arabidopsis and rice genomes has been completed, gene trapping mediated by T-DNA is likely to play an increasingly important role in determining gene function. In this review, we describe the types of gene trapping mediated by T-DNA,the advances in gene cloning, and the mutant pool and its applications. Problems in plant functional genomics are also discussed.