OBJECTIVES: The purpose of this study was to compare the medication compliance estimates among a sample of infliximab-treated Crohn’s disease (CD) using two separate data sources: medical charts and administrative claims. METHODS: A Mid-Atlantic regional health plan provided claims data for their CD population during calendar years 2006-2010.  Claims were aggregated by gastroenterologist tax ID in order to identify providers with the largest CD patient panels for recruitment into a chart review study.  An electronic case report form was developed to aid in the chart data extraction and included fields for demographics, anthropometrics, diagnoses, medications, diagnostic tests, surgical procedures, treatment dose, administered quantity, and service dates.  Once captured, both the chart and claims data were used to quantify medication treatment compliance over one episode of care. RESULTS: One hundred and sixty-one infliximab charts were reviewed and merged with the claims data.  Dosages and vial counts were unavailable in the claims data; therefore, intervals between maintenance infusions were calculated, resulting in a mean maintenance interval of 58 days (± 15) per patient.  Regarding charts, infusion date, dosage, and administered quantity were all available.  Approximately 83% of infliximab patients had a stable dose of 5 mg/kg over the course of their first episode of care, with a mean maintenance interval of 60 days.  Dosing information from patient charts will be used to estimate dosage from claims where charts are not present in an effort to create an algorithm for estimating dose from administrative claims only. CONCLUSIONS: Claims data were less equipped to estimate biologic treatment compliance, while the chart data included many indicators necessary to track biologic dosing patterns.  However, information from claims augmented charts, and provided details on a much larger population of biologic patients, highlighting the importance of utilizing both the get a better depiction of treatment, compliance, and costs.