Arusa (Adhatoda vasica) is an important medicinal plant widely used in Unani system of medicine of (Family-Acanthaceae). The leaves of Adhatoda vasica contain several biologically active phytochemicals such as alkaloids, tannins, saponins, phenolics and flavonoids. It mainly consists of pyrroquinazoline, alkaloids, viz. vasicine, vasicol, vasicinone, peganine along with other minor constituents. The plant possesses diverse pharmacological activities, In Unani system of medicine, the drug is described as having dafa-e-tashannuj (anti-spasmodic), qatil-e-jarasim (antibiotic), mukhrij-e-balgham (expectorant), dafa-e-humma (antipyretic) properties due to which it is prescribed in a wide range of ailments like influenza, tuberculosis, bronchitis, gastric ulcers etc. Leaf juice is beneficial in the treatment of dysentery and diarrhoea. Various other activities like radio modulation, hypoglycaemic effect, cardiovascular protection, antitubercular, antiviral, hepatoprotective and antioxidant activity have also been reported.