Phytoremediation is the direct use of living green plants to degrade, contain, or render harmless various environmental contaminants, including recalcitrant organic compounds or heavy metals. The methods involved include phytoextraction, direct phytodegradation, rhizofiltration, phytovolatilization or formation of artificial wetlands, and lagoon systems. More research background and the development of plants tailored for remediation purposes, using genetic engineering and deeper understanding of plant cooperation with microorganisms is needed. This approach is illustrated by our studies of heavy metal uptake improvement or studies of the PCB conversion, which include in-vitro screening of plant species, analysis of the products, evaluation of their toxicity and field plots, and also studies of enzymes and cloning of foreign genes into plants.