Adenovirus (types 3, 4, 5) was implicated as the etiologic agent in three cases of persistent keratoconjunctivitis. In two, virus was isolated 25 and 29 months after the onset of symptoms; the third patient has suffered intermittent flares of kerato-conjunctivitis since the initial isolation of virus 13 weeks after the onset of the disease. Such patients may represent a previously unsuspected source of adenovirus in the population. All were given corticosteroids topically. This treatment may have prolonged the adenoviral disease.