Adenovirus-associated epidemic keratoconjunctivitis (A-EKC) is a cause of large and prolonged outbreaks in ophthalmology clinics and can result in substantial morbidity. A-EKC outbreaks are often the result of contaminated ophthalmologic equipment, surfaces, or hands. Contaminated multidose eye drops are also a likely culprit, but few prior studies provide clear epidemiologic evidence that adenovirus transmission resulted from contamination of eye drops. We describe an A-EKC outbreak at a large, hospital-affiliated eye clinic that affected 44 patients. The unique epidemiology of the outbreak provides strong evidence that contaminated multidose dilating eye drops resulted in adenovirus transmission. Removal of multidose eye medication from the clinic, combined with case finding, enhanced infection control and enhanced environmental cleaning, led to rapid control of the outbreak.