Biologics prescribed by rheumatologists and gastroenterologists are among the most commercially successful biopharmaceutical products in the world and are prime targets for developers of biosimilars. For companies that expect to market biosimilars or compete against them, understanding the perceptions and expectations of these specialists with regard to biosimilars is paramount. We conducted primary market research with rheumatologists and gastroenterologists in the United States and Europe to understand their perspectives on biosimilars and their expected adoption rates.