Abstract: In this study, effects of different concentrations of glutamin, malic acid, Salicylic acid and their interaction on extending the vase life, total chlorophyll content, ACC-Oxidase activity, anthocyanin leakage, membrane stability and malondialdehyde content of Cut Flowers of 'Prato' Lily was investigated. The vase were placed in chambers at 25°C, relative humidity about 70% and 14 h photoperiod that was maintained using fluorescent lamps (light intensity of 15 μ mol m-2 sec-1) at the top of the corolla. The results showed that glutamin, malic acid and Salicylic acid treatments increased the vase life and decrease the percentage of wilting compared to the control. The vase solution containing 3 mM glutamin and 4 mM malic acid with 2 mM Salicylic acid significantly increased vase life compared to the control, in addition, the malondialdehyde accumulation and ACC-Oxidase activity reduced in the same solution while membrane stability was improved. Results suggest that glutamin and malic acid along with salicylic acid increases vase life by affecting many of the age-related changes associated with Lily petal senescence.