For efficient and profitable crop production, appropriate weed management is essential. Today, herbicides are an integral part of modern farming practice globally, as the), assure the convenient method of weed control chemically. Glutathione S-transferases (GSTs, EC.220.127.116.11) are a superfamily of multifunctional enzymes that detoxify endo- and xenobiotic compounds by conjugating glutathione (GSH) to a hydrophobic substrate. Plant GSTs have been a focus of attention because of their roles in herbicide detoxification and environmental safety. In this study, the application of herbicide called tribenuron-methyl to the cultivars of wheat (Triticum aestivum L. cv. Izgi-2001, Triticum aestivum L. cv. Alpu-2001) and barley plants (Hordeum vulgare L. cv. Bilgi-91, Hordeum vulgare L. cv. Kalayci-97) caused an increase in GST activities of both in roots and shoots. Total GSH and protein contents were also determined for all above-mentioned plants. As a Conclusion, our results indicate that depending on the herbicide itself, treatment conditions and the origin of the plant. tribenuron-triethyl had an effect on the parameters measured in this study, including the GST activities and synthesis of GSH. The maximum increase in enzyme activity was observed in herbicide-treated Triticum aestivum L. cv. Izgi-2001 roots: 192 % of control with a tribenuron-methyl concentration of 1.5 M. However, further investigations are needed to elucidate the presence of specific tribenuron-methyl GST isozymes in this plant.