Neem (Azadirachta indica A. Juss.) is a multipurpose tree with various biological properties and benefits. Different parts of the neem plant (leaves, bark, twigs, seed, oil, etc.) are known to have antimicrobial effects against a wide variety of microorganisms. Owing to this, it has been widely used in Ayurveda, Homeopathy, Siddha and Unani medicines worldwide. Neem products have also found application in agriculture as biopesticides and in food preservation. Vast research has been done and many reports are available on the antiviral, antibacterial, antifungal, anthelmintic and other activities of the plant. This review summarizes the antibacterial role of A. indica in the prevention and management of various bacterial diseases of humans, animals and plants.