The influence of two selenium concentrations (5 and 20 μM) on crop yield, the content of chlorophyll, carotenoids and anthocyanins, as well as accumulation of nickel, selenium and sulphur were studied in the leaves of 50 μM Ni-stressed lettuce plants. Experiments were carried out in water cultures. The obtained results suggest that selenium at concentration of 5 μM in nickel contaminated medium positively affected plants by stimulating their growth, increasing the concentration of assimilation pigments, and thereby at least partially prevented the toxic effect of nickel excess. Moreover, in plants enrichment with selenium a higher increase in content of chlorophyll