In 2017, sales of branded biologics in oncology, immunology, endocrinology, nephrology, respiratory, and ophthalmology, exceeded $80 billion across the major markets (United States, EU5, and Japan). Sales of biosimilars in these same therapy areas and regions totaled approximately $2.5 billion. Throughout our 2017-2027 forecast period, increasing numbers of branded biologics are set to lose patent protection, with biosimilars expected to enter the market and erode both patient share and drug prices. We present out forecasts for key reference brand and their biosimilars by therapeutic area, molecule, and region.