Awareness of consumers regarding the functional food led to an increasing demand for food rich in antioxidants which have a wide range of activities such as antitumoral, antiviral, cardioprotective and antimutagenic activities. Phenolic compounds are an essential part of the human diet and are of considerable interest due to their antioxidant activity. Wastes from fruits represent a major disposal problem for the industry concerned but they are also a promising source of phenolics. Further on this wastes can be used as by-products for further explanation on the production of food additives or supplements with high antioxidant activity. This book is underlying the great potential of the most important by-products of apple, grape and berry fruits processing as a source of antioxidants, but also some practical aspects of extraction and production of natural antioxidants will be discussed.