OBJECTIVES: The objective of this research was to conduct primary research with US managed care decision-makers to understand their perceptions and management expectations for pending biosimilar market availability in the United States. METHODS: Explorative primary research (n=20) was conducted with a sample of Managed Care Organization (MCO) decision-makers composed of pharmacy and medical directors, clinical pharmacists, and field experts involved in evaluating expectations of biosimilar management.  Interviews were conducted from January to March 2011 and consisted of individual one-hour phone cponversations.  Survey development focused on addressing how biosimilar evaluations for plan coverage will be made and vary by therapeutic class including testing of: Erythropoietin-stimulating agents (ESA), cancer monoclonal antibodies (mAb), anti-tumor necrosis factor agents (anti-TNF), and granulocyte-colony stimulating factors (G-CSF). Baseline knowledge that US payers had about biosimilars and abbreviated pathway development was also tested.  Qualitative survey methods for eliciting stated preferences were used.   RESULTS: Payers recognize differences between biosimilars and small molecule generics in molecular structure and manufacturing processes; however, uncertainty exists around exact payer definitions for biosimilarity.  Payers view biosimilars as alternative branded products rather than small molecule generics.  Research also indicated that contrary to review for small molecule generics, formulary review for biosimilar products will likely vary by class since different drugs and indications may require different evidence. Specifically, variance in biosimilar management decisions will vary depending on the sensitivity level to manage the category.  Payers expect biosimilar cost offsets within the range of 11-30% from innovator brands.   CONCLUSIONS: Presently, discussions about biosimilar formulary review have been informal and high-levelt.  Biosimilar product value assessments will differ from the case of small molecule generics and coverage policies will vary by class.  Budgetary and economic impact is the major driver in proposed utilization management controls, but will need to be balanced in light of product comparisons in safety and efficacy.