Human adenoviruses are the most common cause of conjunctivitis in adults and children. It can cause infection of conjunctiva, gut, lungs and liver. Ocular adenovirus can cause non-specific conjunctivitis, pharyngoconjunctival fever, epidemic keratoconjunctivitis and chronic keratoconjunctivitis. Its genome consists of structural and non-structural proteins that help in the attachment and penetration of the viral genome into host cell and nucleus causing viral replication. Host cells have various defence mechanisms to prevent viral infection and virus has mechanisms to counteract the defence. Mediators such as epithelium of the ocular surface and alpha defensins help build innate immune response, whereas T cells, IL8 and interferon gamma help in adaptive immune response. The virus penetrates and attaches to various cellular receptors, leading to the activation of signalling cascades. Replication of virus occurs in early and late stages. Human adenoviruses have tissue tropism due to which specific species of the viruses interact with specific receptors of the host cells. Characteristic clinical features of adenoviral infection commonly include follicular conjunctivitis, pseudo membrane formation, subepithelial infiltrates and follicular lymphadenitis; however, it depends on the phenotypic type.