During the aging of H. syriacus flower, biosynthetic pathways of ethylene and polyamines, their interactions, and their effects on senescence were investigated. The evolution of ethylene in ephemeral flower was rapidly increased immediately after initiation of in-rolling of corolla at which EFE activity became maximum peak. After that, EFE activity was gradually decreased even though the aging was continued. Ethylene production was, however, slightly inhibited by the treatments of AOA and putrescine. The activity of ACC synthase and SAM decarboxylase were most rapidly increased at the time of 36th hrs. The contents of ACC and MACC were gradually increased from the early stage. However, ACC contents was decreased at the final stage but MACC was continuously increased. In normal condition, endogenous level of polyamines exists in the order of putrescine>spermidine>spermine. Putrescine was reduced from the initial point of aging, but spermidine and spermine were reduced from the middle and final stage of aging, respectively.