The interaction between polyamines and ethylene is still not clear for floral tissues. The aim of the present paper is to examine the senescence on the isolated petals of carnation (Dianthus caryophyllus cv. Desio) but not the whole flower in an attempt to clarify the exact role of polyamines. Petals were treated with putrescine (Put; 0.0, 1.0, 10mM), spermidine (Spd; 0.0, 1.0, 10mM), spermine (Spn; 0.0, 1.0, 10mM), Put+Spd (1.0mM), Put+Spn (1.0mM). The fresh weight of petals in all 10mM treatment was decreased less than those in the other treatments at all times but there were no significant differences. The differences in ethylene production were significant. In petals maintained in 10mM of polyamines, ethylene production was completely inhibited until 13 days and senescence was considerably retarded. However, ethylene productions in 1.0mM polyamines treatments were delayed 2-3 days with reduced amounts. These results suggest that high concentrations of polyamines retard senescence and completely inhibit ethylene production. ACC content, activities of ACC synthase and SAM decarboxylase were analyzed. Finally, the role of SAM in ethylene and polyamines biosynthesis will be discussed.