The effects of n-propyl gallate (nPG) on postharvest ripening of tomato have been studied. Mature green (MG) stage tomatoes were harvest and treated with 0.5 mM nPG at 25 ± 1C for 12 h. Following the nPG treatment, fruit ripening was delayed by at least 7 days. Cyanide-resistant respiration and ethylene production were suppressed significantly at the first 7 days. nPG treatment decreased levels of H2O2 and increased activities of antioxidant enzymes and chemicals, particularly for superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (GPX) and ascorbic acid (AsA). The decreases of flesh firmness and total chlorophylls were inhibited, and the production of soluble sugars and lycopene were suppressed by nPG either. Alternative oxidase (AOX) and cyanide-resistant respiration play important roles in fruit climacteric and may be correlated with system 2 ethylene production. nPG could be used as an efficient inhibitor to tomato fruit ripening.