The patent expirations for many biotechnological medicines have prompted the development of copies of biological medicinal products. Unlike generics, biosimilars are similar but not identical to their reference product, because their chemical characteristics are directly related to the manufacturing process which cannot be precisely duplicated. The regulatory policy for biosimilars is complex and in Europe it is regulated mainly by guidelines issued by the European Medicines Agency (EMEA); additional product-class specific guidelines have been developed as in the case of recombinant human erythropoietin (rHuEPO). In 2008, the experience gained with this drug has prompted the development of a new guideline, currently in draft. In this review we critically discuss aspects related to EMEA guidelines, particularly focusing on rHuEPO.