Since July 1973 cases of keratoconjunctivitis resembling epidemic keratoconjunctivitis were observed in the External Eye Disease Clinic at Moorfields Eye Hospital; City Road, London. Adenovirus type 19 was isolated in human embryonic kidney cells from 21 patients. The majority were males between 20 and 40 years old. A small hospital outbreak involving six patients occurred. Clinical features of the disease, consisting of moderate to severe follicular conjunctivitis, major subepithelial punctate keratitis, sometimes with pseudomembrane and scarring, were closely similar to those of epidemic keratoconjunctivitis caused by adenovirus type 8. This similarity, as well as the ability of the agent to cause hospital outbreaks, indicates that adenovirus type 19 is a cause of epidemic keratoconjunctivitis. A case of bilateral chronic papillary conjunctivitis that persisted for 16 months following an acute onset was described. Adeno 19 was isolated from the eye of the patient after 12 months of recrudescent or recurrent illness. Chronic adenovirus infection lacking the usual clinical picture of an acute follicular reaction has not hitherto been described. Such cases are probably important because of the obvious danger of continuing the carriage and shedding of infective adeno 19 from one outbreak to another, by presenting subsequently in eye clinics, and providing an unrecognised source of infection to initiate further outbreaks of hospital transmission.