Clones of 35S-Zmgstf4 transgenic Arabidopsis thaliana expressing the glutathione S-transferase F4 gene of Zea mays was tested for stress-inductive GST (glutathione S-transferase) activity following treatments with the heavy metals Zn (150 and 1500 μM), Cd (20 and 30 μM) and chloroacetanilide herbicide metolachlor (2000 μM). The overexpression of Zmgstf4 gene in Arabidopsis resulted in an extreme resistance to all treatments. The GST activity of the transgenic plants was almost the double compared to the wild type plant in the untreated samples. After Cd (20 and 30 μM), and Zn (150 and 1500 μM) exposure the stress response activity of GSTs increased in both wild type and transgenic plants, however with significantly higher levels in transgenic plants with the extreme level at 20 μM CdSO4 treatment (0.24 in transgenic and 0.13 in wild-type). To compare GST responsivity, Zn treatments was less inductive compared to Cd. Metolachlor (200 μM) was totally tolerated by transgenic plants, compared to wild type plants, which died in 11 days.