Ocimum basilicum (O. basilicum) L. belongs to family Lamiaceae which comprises the most employed medicinal plants as a worldwide source of spices and also as a consolidated source of extracts. The phytochemical constituents of sweet basil essential oil have been investigated for several therapeutic importance from many regions of the world. They include terpenoids, alkaloids, flavonoids, tannins, saponin glycosides and ascorbic acid. These compounds have been reported to exhibit antibacterial and antifungal, antidyspepsia, anti-inflammatory, antioxidant, antiulcer, antiviral, insecticidal, wound-healing etc. activities. The plant parts of O. basilicum have been widely used in preparation traditional medicine. The plants also been used as a folk remedy to treat various ailments such as feverish illness, poor digestion, nausea, abdominal cramps, gastro-enteritis, migraine, insomnia, depression, gonorrhea, dysentery etc. Externally, they have been applied for the treatment of acne, loss of smell, insect stings, snake bites and skin infections. The present review is aimed to cover the pharmacological investigations on this important medicinal herb. Key Words: Ocimum basilicum, phytochemical constituents, antiinflammatory, antioxidant, antiviral, insecticidal