/In this study, a gradual and continual drop of SOD and POD was observed in A. thalian treated with Cr(VI) from 100μM and with Cr(III) from 200μM. CAT activity was not significantly affected by Cr stress except treated with 700μM Cr(VI). Chromium stress significantly increases the activity of APX and GR. APX activity enhanced respectively up to 1.7 and 2.1 times of control for the Cr(III) and Cr(VI) at 200μM. With GR, the highest value was 2.1 fold of control at 500μM Cr(III), 2.9 fold at 300μM Cr(VI). It indicates that enzymes engaged in antioxidant defence: APX and GR were activated by Cr, while SOD and POD activity was inhibited.