The peanut is an important crop grown on over 21 million hectares worldwide. Although peanuts have had an adverse image due to their content in saturated fatty acids, it is important to mention they also are an excellent source of protein, vitamins, and minerals for human nutrition. In addition, peanuts contain relevant bioactive constituents that can provide a wide range of health benefits. Unfortunately, peanuts are also one, if not, the most allergenic vegetables and the most common food-related cause of IgE-mediated allergic reactions, mainly in westernised countries. This book will present an up-to-date overview regarding peanut composition, physical characteristics and bioactive properties. The second part will cover peanut and legume allergen characteristics, together with their prevalence. In addition, the therapeutic strategies to treat peanut allergy and the problem regarding the cross-reactivity of peanut and other allergens will be discussed.