Nitric oxide (NO) was applied to broccoli (Brassica oleracea L. var. italica) florets and analyzed its effect on chlorophyll degradation during postharvest senescence. Florets were treated with 1000 µL/L of NO for 5 h and placed in darkness at 20 °C. During storage, the NO treatment delayed yellowing and retarded the onset of chlorophyll degradation. The activity of lipoxygenase was not related to the development of yellowing during storage. However, the accumulation of malondialdehyde, which could be used as an index of lipid peroxidation, was higher in the control than observed in the NO treatment. In untreated broccoli florets during storage, lipid peroxidation influenced the yellowing of broccoli florets while NO-treated florets maintained chlorophyll levels and decreased lipid peroxidation.