This study has highlighted the role of copper and zinc ions on the intracellular metal levels as well as antioxidant enzyme activities and membrane lipid peroxidation levels in Fusarium equiseti and Fusarium acuminatum. Elevating zinc concentration in the growth medium from 2 to 6 muM Zn2+ results the increases in intracellular zinc levels and the decreases in iron and manganese levels. However, magnesium levels have been unaltered depending on the Zn2+ concentration.On the other hand, SOD and CAT activities of F equiseti and F acuminatum grown in 4 muM Zn2+ were reached the maximum values where the intracellular manganese and iron levels have been determined to be optimum values. These results suggest that the metals, which are cofactor of these enzymes, are effective elicitors. In addition, intracellular copper, zinc and iron levels have been indicated positive correlation with copper concentration of the growth medium. In contrast, manganese levels have been decreased and magnesium levels unaltered with respect to increasing of copper concentration. In the presence of copper, significant inhibition of antioxidant enzyme was observed, while the increases in membrane lipid peroxidation levels were detected in the cells. The results may suggest that the enzymes were inactivated by free radicals produced in Haber-Weiss reaction, which was initiated by toxic concentration of copper and iron metals. (C) 2003 Published by Elsevier Inc.