Lemon balm Melissa officinalis L. belongs to the Lamiaceaemint family. It is one of the oldest and most commonly known medicinal plants. It is cultivated in Poland on a large scale. Lemon balm leaf Melissae folium is the herbal raw material. It contains essential oil (e.g. with citral which provides the plant with characteristic lemon scent), phenolic acid, including rosmarinic, caffeine and hydroxycinnamic acid, flavonoids and bitters. Active substances in the lemon balm provide a relaxing effect in mild conditions of nervous stress and sleep disorders. Moreover, they alleviate the symptoms of gastrointestinal disorders, including flatulence and nausea. It is recommended to combine lemon balm with other materials with similar action in order to increase their strength, such as common hop or valerian.