According to researches aqueous extract of Melissa ofﬁcinalis L. may be a beneﬁcial treatment for patients suffering from benign palpitations as a promising anxiolytic drug without any considerable side effects. Lemon balm (Melissa officinalis L.) is a well-known medicinal plant from Lamiaceae family. It is an aromatic herb native to southern Europe, Asia Minor and North Africa. As a perennial plant it grows to the height of 30–125 cm, with soft short hairs surrounding all parts. Leaves are petiolate, ovate, to 6 cm long. Flowers are white or pale pink consisting of small clusters. Phytochemical investigations have revealed the presence of volatile compounds, triterpenes, phenolic acids and flavonoids as the main active constituents of M. officinalis. The plant has been used for the treatment of mental and CNS diseases, cardiovascular and respiratory problems, various cancers, and as a memory enhancer, cardiac tonic, antidepressant, sleeping aid and antidote. In Traditional Iranian Medicine (TIM), Melissa ofﬁcinalis L. is commonly regarded as an effective therapy for heart palpitations. Heart palpitation is deﬁned as an abnormal, unpleasant or heightened awareness of heartbeat. It is a common complaint that is often benign and associated with a marked distress that makes the condition difﬁcult to treat. It is the second most common reason in general practice for which patients are referred to a cardiologist. The recent study is conducted to evaluate the effect of aqueous extract of M. ofﬁcinalis leaves on patients with heart palpitation. Eligible volunteers were randomly assigned as patients to a 14 day treatment with 500 mg twice a day of lyophilized aqueous extract of M. ofﬁcinalis leaves (or placebo). The results showed that this treatment reduced frequency of palpitation episodes and signiﬁcantly reduced the number of anxious patients in comparison to the placebo. Also, M. ofﬁcinalis extract showed no indication of any serious side effects.