OBJECTIVES: The emergence of biosimilars for blockbuster therapies such as Remicade, Humira, Enbrel and Rituxan/MabThera is changing the paradigm by which traditional market access decisions are made for biologics. Furthermore, the regulatory pathway in Europe and the U.S. has raised uncertainties among clinicians regarding both the efficacy and safety of biosimilar molecules. The objectives of our research were to (1) understand the evolving mechanisms for biosimilar market access, (2) identify the key stakeholders involved in access decisions or influence and (3) determine the value drivers of biosimilars across diverse stakeholder groups.  METHODS: A large sample of stakeholders (n=271) were engaged, including clinical specialists, payers and patients, across Europe and in the U.S. We performed in-depth qualitative interviews to gain an understanding of the current landscape for biologics and expectations for biosimilars, focusing on RA, Ulcerative Colitis, Crohn’s Disease and Psoriasis.  RESULTS: Our research indicates the fundamental understanding of biosimilars is inconsistent both within stakeholder groups and across different groups. Furthermore, for clinicians, a lack of accurate understanding of biosimilars can be a substantial driver of negative perception and a key barrier to anticipated adoption. Overall, each stakeholder group that will influence biosimilar market access has different value needs and expectations from biosimilars.  CONCLUSIONS: Our findings highlight the need for a more consistent definition of biosimilar and clinical data requirements and a tailored approach to value communication for key influencers and stakeholders in the biosimilar value chain.