In order to investigate whether defense genes PAL, LOX, PBZ1, PR 1 a and Cht 1 participate in APR(adult plant resistance)to rice bacterial blight, their expression were analyzed using RT-PCR. Enzymatic activities of PAL and LOX were also measured. Results indicated that PAL was induced by pathogen and wounding in adult plants while it only induced by pathogen at the seedlings, and the expression of PAL was stronger in adult plants than that in seedlings. Expression of LOX was induced by pathogen both in seedlings and adult plants and it was stronger in adult plants than that in seedlings. Expression PBZ1 was induced by both pathogen and wounding in both seedlings and adult plants and it is earlier and stronger in adult plants than that in seedlings. No expected fragments were obtained for PR 1 a and Cht 1. Enzymatic activities of PAL and LOX were consistent with their mRNA accumulations, respectively. It is probable that activation of PAL,LOX, and PBZ1 play crucial roles in APR to rice bacterial blight.