Continuous postharvest treatment of carnation flowers (Dianthus caryophyllus L. cv. Elliot's White) with 50 or 100 mM aminotriazole significantly extended useful vase life relative to flowers held in distilled H2O. No morphological changes symptomatic of floral senescence appeared in treated flowers until 12 to 15 days after harvest. The longevity of aminotriazole-treated flowers was extended to ≈18 days. The respiratory rate of aminotriazole-treated carnations was suppressed, and they exhibited no respiratory climacteric throughout the period of observation. The responsiveness of aminotriazole-treated flowers to exogenous ethylene appeared temporally regulated. Flowers treated with 50 mM aminotriazole for 2 days senesced in response to application of 10 μl exogenous ethylene/liter, whereas flowers treated for 24 days exhibited no morphological response to ethylene treatment. Chemical name used: 3-1H-amino-1,2,4-triazole-1-yl (aminotriazole).