In recent years, biosimilars of epoetin alfa and filgrastim have been approved and launched in major markets. Uptake of these products among oncologists is increasing, driven by payers and regulatory organizations looking to reduce healthcare expenditure and deliver enhanced value for money. The recent launch of Zarxio – the first biosimilar to receive a marketing approval from the FDA – is a testament to the growing acceptance of biosimilars and a milestone for the US healthcare system. To secure a foothold in the exciting new market created by biosimilars, or defend against biosimilar erosion, manufacturers and marketers of reference brands and biosimilars need to understand the perceptions and expectations of oncologists. To this end, Decision Resources Group conducted extensive primary market research with medical oncologists and hematologist-oncologists in the United States and Europe to generate insights on a range of key topics; these include physician familiarity, preference and concerns relating to biosimilars, automatic substitution and switching, indication extrapolation, drivers and barriers to uptake, reimbursement and clinical data requirements. Based on this extensive market research, this report also provides highly granular, brand and biosimilar market forecasts across the seven major markets for biologics: the United States, EU5, and Japan.