Abstract: The activity of polyamine oxidase in embryonic axes during peanut (Arachis hypogaea ) seed germination was investigated. Peanut seeds were soaked for 12 h and allowed to germinate at 30℃ in moistened vermiculite. The PAO activity did not appear within the first 12 h of germination, but occurred when the germination time was 24 h and increased from then on. The PAO activity was higher when the peanut seeds germinated in the dark than in the light (1600 Lx). When the peanut seeds were treated with 10 mg/L actinomycin D (Act-D), a RNA sunthesis inhibitor or cycloheximide (CHM), a protein synthesis inhibitor for 96 h, the inhibitions of germination and PAO activity were 26.3% and 41.1% by Act-D or 87.3% and 94.0% by CHM. All of these results suggested that PAO was involved in the peanut seed germination.