Heavy metals are the major environmental pollutants, mainly in areas with high anthropogenic activities. In this study, the effects of three cadmium (Cd) concentrations (30, 60, and 120 mg^-1l) alone and in combination with two concentrations of SiO₂ nanoparticles (10 and 100 mg^-1l) on growth and some physiological parameters of wheat (Triticum aestivum) seedlings were investigated. Cadmium treatments decreased the fresh and dry weight of roots, shoots, chlorophyll, carotenoid and total protein contents of the leaf tissues significantly. It also increased the amount of proline, lipid peroxidation and catalase activity of wheat seedling. The toxic effects of cadmium ions on growth and physiological activities of wheat seedlings were reduced in the presence of SiO₂ nanoparticles.