A study about the incidence of Adenovirus on viral conjunctivitis was conducted. A sample design was made and samples of conjunctival exudate were taken from 150 patients with diagnosis of apparently viral conjunctivitis at the "Ramón Pando Ferrer" Ophthalmological Hospital from July to December, 1994. Samples were inoculated in cell culture and the indirect immunofluorescence technique was applied to those with a cytopathogenic effect that suggested infection due to Adenovirus. Monoclonal antibodies were used against Adenovirus allowing to identify them as part of the Adenoviridae family. The hemagglutination technique was used with erythrocytes of monkeys and rats as an indicator system in order to group the isolates previously identified by the indirect immunofluorescence technique. Later on, it was made an analysis by restriction enzymes of the viral genome to enable typing. The results of this study showed an incidence of Adenovirus on viral conjunctivitis of 20%, with a confidence interval between 14 and 26% and a reliability index of 95%. It was proved that serotype 37 caused conjunctivitis more frequently.