Tomato fruit is an important source of vitamin C, but varieties are not usually cultivated according to their vitamin C content. In addition, the effect of cultural practices and pre- and postharvest treatments on vitamin C content is not commonly taken in consideration. In a controlled experiment, where fruit were compared objectively for maturity stages using color measurements (a*, b*, L*, hue angle, chroma) we have evaluated the production of ascorbic acid (AsA) content and the activity of ascorbate oxidase (AsO) and ascorbate peroxidase (AsP) during maturation and ripening of the fruit on the plant, or during ripening with ethylene. Ethylene-ripened fruit were harvested at the mature green stage. AsA increased during maturation and ripening and started to decrease after full red color development. The decrease in AsA content was correlated with an increase in the activity of AsO and AsP. Fruit ripened with ethylene had significantly less AsA content, and higher activity of AsO and AsP than those ripened on the plant.