On March 23, 2010, President Barack Obama signed into law the Patient Protection and Affordable Care Act, which contains the Biologics Price Competition and Innovation Act. Biosimilars have an important role in the United States health care system, and this new law creates an abbreviated approval pathway for biosimilar products in the U.S. A biosimilar is a biologic product demonstrated to be highly similar to an approved innovator biologic product (“reference product”). While the law provides general information on the standards to demonstrate biosimilarity, Congress has authorized the FDA to define the scientific standards and content of biosimilar applications. There is an increasing global interest in the development of biosimilar products, and several regulatory authorities around the world, as well as the World Health Organization (WHO), have established regulatory guidelines for the approval of biosimilars. The scientific standards and requirements in the biosimilar guidelines of the WHO and other health authorities, including the European Union, Canada, Japan, and South Africa, are reviewed in this paper. The similarities as well as the differences among the policies adopted by these regulatory authorities may provide the FDA valuable information as the agency develops its standards and approaches for the approval of biosimilars in the U.S. At the same time, while establishing such approaches, the FDA has the opportunity to demonstrate leadership in addressing significant safety and other issues related to multi-source biologics and biosimilars that remain a global challenge.