Abstract: The characteristics of photosynthetic metabolism, during treatment with cadmium, in two stories of sunflower seedlings were investigated. After 7 days of application of the metal, chlorosis and necrosis appeared especially in the first story. These stories approved a high decrease in the amount of Fe and Mg, this decrease was more important in the first story. Pigments were analyzed in the two stories and a significant decrease was recorded. However, no changes observed in the maximal efficiency of PSII photochemistry (Fv/Fm). Furthermore, the majority of carboxylation enzymes showed a decrease of their activity. Results of the present study suggested that the photosynthetic apparatus remained functional after Cd exposition and showed a tolerance for this metal despite effects on growth, mineral nutrition and enzymes activities.