The chlorophyll content during the maturation of the sweet pepper fruit decreased steadily from the Green to the Yellow/Green stage ; subsequently, there was a significant decrease to the Yellow stage. Conversely, carotenoid content increased steadily. Hydrogen peroxide increased 2.5 fold between the Green and the Green/Yellow stage ; it then declined slowly from the Yellow/Green to the Yellow stages. Yet the final level was higher than that in the Green stage. Superoxide dismutase (SOD) activity increased from the Green to Yellow/Green stage, as did the ascorbate peroxidase (APX) activity. The trends in SOD and APX activities during the maturation of the sweet pepper fruit paralleled that of hydrogen peroxide. Glutathione reductase activity also increased from the Green to the Green/Yellow stage. However, catalase activity remained nearly constant during the maturation. These results indicate that the activity of antioxidative enzymes could be enhanced because of the accumulation of hydrogen peroxide during the maturation of the sweet pepper fruit.