Conjunctivitis is a common condition of the eye that occurs worldwide and affects all ages and social strata, affecting more than 2 percent of the population. It is caused by a variety of bacterial or viral pathogens but may also be caused by allergies, irritants or medications. Most types are self-limiting, but some may progress and cause serious complications. Health care providers have low clinical accuracy at differentiating the various etiologies of acute conjunctivitis. In this paper we review the epidemiology and economic burden of conjunctivitis. The main methods are a comprehensive review of the literature supplemented by analysis of medical claims data.