The genus Mentha L. (Lamiaceae) is distributed all over the world and can be found in many environments. Mentha species, one of the world's oldest and most popular herbs, are widely used in cooking, in cosmetics, and as alternative or complementary therapy, mainly for the treatment of gastrointestinal disorders like latulence, indigestion, nausea, vomiting, anorexia, and ulcerative colitis. Furthermore, it is well documented that the essential oil and extracts of Mentha species possess antimicrobial, fungicidal, antiviral, insecticidal, and antioxidant properties. The economic importance of mints is also evident; mint oil and its constituents and derivatives are used as lavoring agents throughout the world in food, pharmaceutical, herbal, perfumery, and lavoring industry. To provide a scientiic basis for their traditional uses, several studies have been conducted to determine the chemical composition of mints and assess their biological activities. This chapter describes the therapeutic efects and uses of Mentha species and their constituents, particularly essential oils and phenolic compounds; some additional biological activities will also be considered.