Entomopathogenic nematodes are a special category of nematodes that can kill an insect within 72 hours along with their symbiont bacterial populations. These nematodes naturally maintain a symbiotic relation with specific enteric bacteria. Because of their high pathogenicity and reproductive potential, entomopathogenic nematodes are used worldwide for biological management of various insect-pests of agricultural crops. This article provides a brief introduction to entomopathogenic nematodes, and discusses important aspects of their biology, mass production, use in agricultural pest management, and its brief history in India.