Pretreatment for 6 h with low concentrations of 1-MCP (1-Methylcyclopropene, formerly designated as SIS-X), a cyclic ethylene analog, inhibits the normal wilting response of cut carnations exposed continuously to 0.4 l·l^–1 ethylene. The response to 1-MCP was a function of treatment concentration and time. Treatment with 1-MCP was as effective in inhibiting ethylene effects as treatment with the anionic silver thiosulfate complex (STS), the standard commercial treatment. Other ethylene-sensitive cut flowers responded similarly to carnations. In the presence of 1 l·l^–1 ethylene, the vase life of 1-MCP-treated flowers was up to 4 times that of the controls.