Changes in gas exchange, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity, PSII and PSI photochemistry, andantioxidant enzymatic activities of tomato leaves were analyzed under chilling in the dark at 9 and 6 ◦C. Their recovery at 15 ◦C was also determined. This procedure was done to gain insight into the relationships among CO2 assimilation, photosynthetic electron transport, photoinhibition, and the antioxidant system in dark chilled tomato leaves.