Abstract: [Objective] To analyze the T-DNA integration pattern in the genome of grey mold Botrytis cinerea. [Methods] T-DNA (Transfer DNA) inserted mutant library of Botrytis cinerea was created by Agrobactirium tumfacience mediated transformation. By using TAIL-PCR (Thermal asymmetric interlaced polymerase chain reaction), we amplified and cloned the chromosomal regions flanking T-DNA insertions. The obtained T-DNA flanking sequences were subjected to alignment with standard T-DNA border sequence for identification and analysis of integration. [Results] Up to 69% T-DNA inserted at noncoding regions and 30% inserted at exons. Recombination including deletion or addition of bases in T-DNA region was observed. The right borders of the T-DNA were frequently truncated, and by contrast the left borders were less prone to degradation and appeared to have been inserted in a relatively integrated manner. Extra sequence additions also occurred in T-DNA integration sites. [Conclusion] Analysis of T-DNA integration pattern in B. cinerea genome will stimulate the functional genomics study of this fungus.