Biosimilars (or follow-on biologics) are a new class of medicine which enters the market subsequent to a previously approved version. They have demonstrated similarity to innovator biologic products in terms of quality, safety, and efficacy. The EMA has taken the lead in the regulatory approval framework for biosimilar products, and WHO has published guidelines on the evaluation of biosimilars in order to facilitate the global harmonization. Based on EMA and WHO guidelines, many other countries such as Canada, Japan and Korea have also issued their own guidance for evaluating follow-on biologics. The US FDA was authorized to approve follow-on biologics by the BPCI Act passed by the US Congress on March 23, 2010, and has just issued a draft guidance in early 2012. The basic concepts and main principles of approving biosimilars are similar among various nations, notwithstanding some differences in regard to the scope, the choice of reference product, and the data requirement. This article reviews the regulatory approval pathway of biosimilar products in different regions.