Cadmium (Cd) is easily absorbed by the root system in many plant species and due to its solubility in water and toxicity is considered as a major pollutant. The aim of this study was investigation of cadmium toxicity on some physiological characteristics of lentil seedlings. So, two-week-old plantlets were treated with different concentrations (0 as control, 0.125, 0.25, 0.5, 1, 2.5 and 5 μM) of cadmium chloride for 10 days and then the amounts of photosynthetic pigments, proline and soluble proteins were investigated. Survey results indicated that with increasing in cadmium concentration, a significant decrease was observed in photosynthetic pigments. In addition, the cadmium significantly was increased amount of proline in treated seedlings compared with control. Also, cadmium has imposed drastic decrease in total soluble proteins and the amount of proteins declined progressively with increasing concentrations of cadmium. Due to a decrease in protein content and photosynthetic pigments, the present results allow us to conclude that the lentil plants showed a negative response to cadmium toxicity. In addition, to overcome cadmium stress, seedling have increased the amount of non-enzymatic antioxidant compounds such as proline.