Abstract: From the antiquity, the ellagitannins have formed an important part of human diet. With a great relevancy in the field of science and technology, several studies have reported the important benefits of ellagitannins to human and animal health. However, the knowledge and application of these compounds in seriously limited due to their complexity and diversity. One of the unknown facts of ellagitannins is their biodegradation, but it is well known through this process is possible to get the monomeric unit, the ellagic acid, which is a product from the hydrolysis of ellagitannins and represents a high added value compound due to his biological properties. The first chapter of this work includes information on ellagitannins, their classification and properties, biosynthesis, biodegradation, ellagic acid production and potential applications. Special attention has been focused on the biological properties of ellagitannins.