The cell system that detoxificates organic xenobiotics comprises three stages. Each of them involves a number of enzymes that, depending on the character of the degraded organic compound, lead to its transformations. The enzymes of the first stage – bioactivation – are generally polysubstrate mono- oxygenases, flavine-containing monooxygenases (FMO), and the enzymes showing hydrolytic and oxido- reductive activity. Induction of the enzymes influenced by xenobiotic has been confirmed by the SAGE studies (Serial Analysis of Gene Expression). The products of the first stage become the substrates of the second stage, that is the stage of conjugation with endogenous substrate. Couplings with glucose catalyze the UDP-dependent transferases with the aminoacid-N-acetyl transferase (ACT), while those with gluta- thione – the most diversified divided into 5 classes and consisting of 20 isoenzymatic forms – the glutathione transferase family (GST). The transport of the resulting conjugates through tonoplast is led by the Mg group and ATP-dependent transporters (ATP-binding Casette). The xenobiotics accumulated in a vacuole are further modified under the influence of peroxidases and carboxypeptidases. Except for the enzymes involved in the three stages of detoxification of organic compounds, there is an enzymatic system for cell antioxidative protection, conditioning the level of plant tolerance to stress caused by organic contamination, which is also very important in the degradation process.