There are several important reasons for stakeholders to be optimistic about prospects for biosimilars. During the past few years, questions about the underlying technology and market acceptance have begun to resolve themselves in a positive manner. Regulatory pathways are being defined, and major players and investments are lining up. Most importantly, a number of patents are set to expire on leading biologics, and financially strapped payers across the globe are anxious to embrace biosimilars and their promise of cost savings. Yet questions and uncertainties remain, and the path forward likely holds some surprises.