Callus tissue of Coker 312 adapted to grow at 150 mM and 250 mM NaCl showed significant increases of glutathione S-transferase activity (GST) compared to callus tissue grown at 0 mM NaCl. Greenhouse-grown salt-tolerant Acala 1517-88 plants treated with either O or 150 mM NaCl were also analyzed for differences in GST activity. The Acala 1517-88 exhibited increased levels of GST when stressed. The NaCl-induced increase in the activity of GST suggests that this enzyme may increase the cell's ability to respond to lipid peroxidation induced by salt stress.