OBJECTIVES: 1) Review all Medicare national coverage determinations (NCDs) from 2007 through 2011 to identify how CER was explicitly an impetus for or considered in the decision, and 2) Make inferences on Medicare’s future use of CER from past behavior and recent health reform developments. METHODS: We reviewed documentation to identify whether a comparative study or health technology assessment (HTA) was cited in Medicare’s decision initiation rationale or referenced in the decision.  Specifically, we determined the: 1) Number of NCDs and degree to which CER was used; 2) Types of products and services (e.g., device, procedure); 3) Therapeutic areas; 4) Organizations producing technical CER materials; 5) Inclusion of cost effectiveness; and 6) Frequency and content of a coverage with evidence development (CED) requirement.  We characterized Medicare’s historical coverage and payment behavior and prognosticated on how aspects of health reform may affect future CER use. RESULTS: More than 55% or 36 NCDs considered CER, with radiological procedures and diagnostic/screening tests comprising over half. Sources for the CER technical work were 5 US and 5 international organizations.  Eleven of the decisions considered cost effectiveness; 4 reported a cost-effectiveness ratio.  While a minority, CED judgments increased over time. Medicare has historically covered and set reimbursement levels that allow for the cost of care plus some profit, only recently and selectively considering evidence of comparative clinical or cost effectiveness.  While provisions of the Affordable Care Act and regulatory changes promote the greater use of CER, there are official and practical impediments that serve as a counterbalance. CONCLUSIONS: Medicare increasingly will use CER in making NCDs but in ways less straightforward than predicted.  While many methods are available to Medicare, perhaps the most promising in the current political environment are evidence threshold “creep”, CED, and several novel applications of CER to coverage, coding, and pricing.