A greenhouse experiment was carried out 2006/2007 and 2007/2008 growing seasons to study the effect of some natural additive materials, sugarcane bagasse, rice straw and gypsum on tribenuron methyl herbicide and cadusafos nematicide side effects on Glutathione S-transferase activity (GST) activity of wheat plant and growth. The results showed that rice straw significantly increased GST during the 1st and 2nd growing seasons compared with the untreated plant. Also, sugarcane bagasse and rice straw showed its peak at the rate of 160 kg/fed., at the 1st season (109.86 and 146.32 IU/mg protein) and 2nd season (158.13 and 305.67 IU/mg protein) growing season, respectively. In the contrary, gypsum treatment effect was decreased gradually with increasing dose, reaching its peak at the rate 40 kg/fed. Results of fresh weight showed that all additive materials treatments affected the fresh and dry weight of wheat plant during the two growing seasons significantly. From the above mentioned results it could be concluded that rice straw reduce the side effects of TBM and cadusafos pesticides and significantly increased GST activity and showed the highest increasing effect on fresh weight and dry weight.