We describe a nosocomial outbreak of keratoconjunctivitis at the Ophthalmology Clinic in Hospital Carlos Van Buren, that affected 150 patients, during August and September of 2006. This outbreak was concomitant with a community outbreak produced by the same agent in the city of Valparaiso that affected 681 other patients. Although adenovirus was not isolated in the nosocomial cases, positive cultures were obtained from community cases, so the diagnosis was based on clinical and epidemiological criteria. The infection rate within the Clinic patients was 5.2% considering the population that attended the Clinic in this period. The evaluation of patient care practices showed that common risk factors among affected cases were measurement of ocular tension with a tonometer in the Ophthalmology Clinic (without disinfection of the tonometer between patients), contamination of work surfaces (equipment, furniture), and poor compliance of hand hygiene. Control measures adopted were cleaning, disinfection of tonometer, equipment and work surfaces, and reinforcement of hand hygiene measures. With these measures, it was possible to control the nosocomial outbreak, despite the continued outpatient care of community-acquired cases.