The present review article explains medicinal and therapeutic uses of Tulsi plant in traditional medicine. Tulsi (Ocimum sanctum [OS] Linn.) is an aromatic plant belongs to family Lamiaceae. It is traditionally used for preparation of various Ayurvedic formulations for treatment of bronchitis, influenza, and asthma. Hot concoction of Tulsi leaves is usually provided for immediate relief in cold, sneezing nose, cough, malaria, and dengue. This article explains the biological effectiveness of OS against diabetes mellitus, hypertension, cancers, respiratory diseases, arthritis, various microbes, and parasites. Tulsi extracts and its various bio-organic constituents showed antioxidant activity, anti-atherogenic effect, anti-aging, immunomodulatory, anti-inflammatory, antistress, hepatoprotective, radioprotective, antihelmintic, repellent and larvicidal activity. Tulsi active ingredients showed anti-inflammatory properties and also play a role in modulation of both cellular and humeral immunity. Plant shows healing properties in hepatic injury and gastric ulcer. It relieves from stress, restore and improve body immunity and digestion. Ocimum basilicum L. contains (-)-linalool, eugenol and methyl chavicol, methyl chavicol (93.0%), gamma-caryophyllene as major constituents. Minor oil constituents are (+)-delta-cadinene, 3-carene, alpha-humulene, citral, and (-)-trans-caryophyllene. Tulsi oil contains high alpha-linolenic acid contents mainly eicosanoid precursor polyunsaturated fatty acids which are anti-inflammatory in nature. Tulsi also contains camphor, caryophyllene oxide, cineole, methyleugenol, limonene, myrcene, and thymol, which are known insect repellents. Its essential oil (EO) can be used to abate the growth of mosquitoes and control malaria. It is a good repellant and can be used for deterring flies, mosquitoes and insects. No doubt Tulsi plant is a good source of natural products mainly phyto-constituents and EO which can be used as alternative medicine for the treatment of various ailments and human health problems but proper composition and appropriate formulation is required before being used.