ABSTRACT: Plant steroids have been implicated to relieve changes induced by heavy metals in plants. Maize (Zea mays L.) seeds were primed with stigmasterol (100 ppm) then grown under different levels of copper in the soil (0, 100, 150, or 200 mg kg-1 soi l ) for 40 days. Stigmasterol pretreatment improved the growth of Zea mays plants compared wi th untreated plants under di fferent copper levels. Moreover , stigmasterol pretreatment enhanced membrane stability index, protein and proline content, as well as the activi ties of nitrate reductase, carbonic anhydrase, peroxidase and catalase. Additionally, grain priming with stigmasterol enhanced the content of photosynthetic pigments in maize plants. Therefore, our results revealed that seed priming with stigmasterol could enhance the tolerance of Zea mays plants grown under high levels of copper .