ABSTRACT: Eosinophilic esophagitis (EoE) has become a major cause of upper gastrointestinal morbidity in children and adults. However, there are few data on the nationwide prevalence of EoE. We aimed to estimate the prevalence of EoE in the United States.We collected health insurance claims from a large database that represented the U.S. commercially insured population. We analyzed data from 2008 to 2011, identifying cases of EoE by using a previously validated definition, and calculated a period prevalence by using data from 2009 to 2011. EoE was defined as any instance of the International Classification of Diseases, 9th revision code 530.13. We calculated the prevalence of the code in the database and standardized the estimate to the U.S. population.Of 35,575,388 individuals in this database, 16,405 had at least 1 code for EoE. The mean age was 33.5 years, 65% were male, 55.8% had dysphagia, and 52.8% had a diagnostic code for at least 1 allergic condition. Among 11,569,217 individuals with continuous insurance coverage between mid-2009 and mid-2011, 6513 had at least 1 code for EoE. When standardized to the U.S. population, the estimated period prevalence of EoE was 56.7/100,000 persons, translating to approximately 152,152 cases in the U.S. Prevalence peaked in men 35-39 years old, with a rate of 114.6/100,000 persons.Despite its relatively recent description, EoE is frequently diagnosed in the United States, with an estimated prevalence of 56.7/100,000 persons. This estimate depends on the accuracy of the International Classification of Diseases, 9th revision code, but it could be an underestimate, because knowledge of the code and recognition of EoE are increasing.