OBJECTIVES:  To evaluate the prevalence and incidence of hepatitis A in a managed care population, segmented by a range of characteristics including age, gender, geography, and health insurance plan. METHODS: This was an observational retrospective cohort study utilizing medical and pharmacy claims data for January 1, 2005 through December 31, 2008 from the Impact National Managed Care Database (Benchmark Database). The index date was defined as the date of the first and only diagnostic claim for hepatitis A within the intake period. All prevalence results reported below are per 100,000 and incidence is presented as per person years. RESULTS: Out of a total of 94,985,124 subjects in the database, females and males were represented equally (51% and 49% respectively).  The 45-64 year age group had the greatest percentage of subjects.   The prevalence of hepatitis A among men and women were almost equal (9 and 8, respectively).  The 45-54 years age group had the highest hepatitis A prevalence (4) followed by the 25-34, 35-44, and 55-64 age groups (3 for each group). The largest hepatitis A prevalence rate was from the northeast region (7) followed by the south (6). In the 2005-2008 timeframe, hepatitis A prevalence was similar in each year (4). Incidence rates across age, region and specific zip codes in person years were less than 1 person per year.  The incidence was slightly higher in  males.  Among three digit zip codes, the zip codes “100” showed higher incidences each year with higher prevalence.  CONCLUSIONS: In a large commercially insured US population, we observed similar prevalence rates of hepatitis A for males and females. The disease was most prevalent in the 45-54 years age group. The northeast had the highest prevalence rate from 2005-2008.