Long vase life is the most important factor determining the economic value of cut flowers. The effect of the pulse treatment of sodium nitroprusside (SNP) was studied at four levels of 0, 20, 40, and 60 µM on the vase life of cut roses (Rosa hybrida L.), lisianthus (Eustoma grandiflorum), and sunflowers (Helianthus annuus L.) in a factorial experiment based on a randomized complete design with three replications and 12 treatments. The results showed that the longest vase life of cut roses (14.33 days) and sunflowers (14.5 days) were obtained from the application of 40 µM SNP whereas cut lisianthus flowers exhibited the longest vase life (14.00 days) when they were treated with 20 µM SNP. This treatment was the most effective in conserving the dry matter of cut roses. SNP significantly reduced ethylene synthesis in cut roses and lisianthus versus the control. The lowest ethylene synthesis in cut sunflowers (0.03 nll-1h-1g-1 FW) was, however, obtained from the treatment of 60 µM SNP. SNP had no significant effect on water uptake, vase solution and stem-end bacterial population, and chlorophyll b. But, it significantly contributed to maintaining the protein content of the studied cut flowers. Overall, it can be said that SNP improves the postharvest longevity of cut roses, lisianthus, and sunflowers by suppressing ethylene synthesis and protecting proteins. تفاصيل المقالة