This chapter reviews the current status of research on investigations of the free radical chemistry of green tea and its constituent polyphenols (GTP). It is based on the use of electron paramagnetic resonance (EPR) spectroscopy, and also includes a section on practical aspects of the technique, which should be of value to readers who are unfamiliar with the detailed operation of EPR. The free radical chemistry of GTP is important, because many of their antioxidant functions involve reactions with O(2)-derived free radicals, and the products of such reactions are themselves generally free radicals. The stability of these products and their abilities to participate in subsequent reactions may have considerable bearing on their biological function. These are also discussed briefly along with the authors' views of future investigations which would appear to be valuable for this topic.