Medical claims can be a primary data source for translational research. This presentation provides information on the All-Payer Claims Database (APCD), a major source of claims data which is now available for Massachusetts through the Center for Health Information and Analysis. Information provided includes: population included, years covered, types of data available, special issues, types of questions that can be answered, and an example of an actual analysis. This presentation was part of the retreat mini-symposium entitled: Big Data: Medical Claims Data for Translational Research.