ABSTRACT Enlist™ technology confers resistance to 2,4-D herbicides, glyphosate, and ammonium glufosinate for soybeans. However, the application of herbicides to plants can generate stress, even in resistant crops. Thus, here we evaluated whether the application of herbicides in transgenic soybean farms, resistant to these herbicides, adversely affects the activity of antioxidant enzymes and porphobilinogen formation by delta-aminolevulinate dehydratase (ALA-D) activity. At seven days after herbicide application, the aerial part of the plants was collected and used to determine the activity of antioxidant enzymes as catalase, ascorbate peroxidase, and guaiacol peroxidase, such as lipid peroxidation levels and the activity of the ALA-D enzyme. At seven days after herbicide application, the aerial part of plants was collect and used to determine the activity of antioxidant enzymes, such as catalase, ascorbate peroxidase and guaiacol peroxidase, as well as the levels of lipid peroxidation and the activity of the ALA-D enzyme. The activity of important antioxidant enzymes involved in the scavenging of reactive oxygen species (ROS) was increased in the soybean cultivar with the Enlist™ technology, while no severe damage to lipids was detected. However, the activity of ALA-D was inhibited, which could potentially impair the formation of porphobilinogen and decrease photosynthetic efficiency. Thus, these results indicate that herbicides can affect the activity of ROS-scavenging enzymes even in transgenic, herbicide-resistant plants.