Ocimum sanctum is generally known as tulsi. It is widely branched and erect, stout and aromatic herb, which grows about a height of 75 cm. This herb is found mostly throughout India and is cultivated in Hindu houses and temples. The various parts of the plant like leaves, seeds and root of this plant have been used in Ayurvedic medicine. The plant has been used in ailment of different disorders and it is having the various activities like antidiabetic, antimalarial, anti- stress, antioxidant, hepatoprotective, antibacterial, antiviral, antifungal, immunomodulating, antiinflammatory, antipyretic, antidiuretic, and hypolipidemic properties with a wide range of safety. In Ayurvedic medicine this plant is being used either alone or in combination with different drugs in various clinical conditions like anxiety, bronchitis, fever, chronic cough, snake and scorpion bites. The plant has many nutrients and other biological active compounds. The main active compounds that have been identified and extracted are ursolic acid and eugenol (an essential oil). The present objective of the work is to highlight the various chemical constituents and different pharmacological activities of the plant against various disorders. Keywords: Ocimum sanctum, Tulsi, Ayurveda, Rama tulsi, Krishna tulsi