Experiments with 6 contrasting bread (Triticum aestivum L.) and durum (Triticum durum Desf.) wheat genotypes grown under field conditions have been carried out to study the effect of soil drought on antioxidant enzyme activities. Native polyacrylamide gel electrophoresis (PAGE) revealed the presence of 1 isoform of catalase, 6 isoforms of superoxide dismutase, 7 isoforms of ascorbate peroxidase and 7 isoforms of glutathione reductase in wheat leaves during drought. Mn-, Fe-, Cu/Zn containing isoforms of one of the key antioxidant enzymes - superoxide dismutase-were shown to function in wheat plants. It was concluded that drought caused increases in APO, SOD, CAT and GR activities in wheat leaves compared with their initial levels. Increases in APO and GR activities were more pronounced, indicating an intense work of the ascorbate-glutathione cycle, which breaks down H2O2.