Green tea is one of the most consumed beverages in the world. Presently, Camellia sinensis has become a source not only for the development of several food extracts but also nutraceutical, cosmetic and medicinal purposes. The technology developed to produce these extracts aims to improve the organoleptic characteristics of the products as taste and smell, and their shelf life. But it also searches to demonstrate some medicinal attributes like antioxidant, anti-aging, anti-tumor and anti-viral activities in relation to the chemical composition of the green tea catechins, especially (-)-epigallocatechin gallate (EGCG). The target of this review is to present the various patents related to the extraction methods and their claims, and to discuss the evidence found in the literature about the pharmacological activities of green tea. It summarizes the recent progress in technology to obtain the green tea extract and in clinical studies on its applications. Health-promoting products and disease-preventing applications of green tea extract or compounds isolated from it also take part of this text.