The legal framework for biosimilar medicinal product was first established in 2004 in the European Union and later in the USA. Since then, based on the scientific and regulatory experience with biosimilarity assessment, regulatory approaches have evolved considerably. A clear understanding of the capabilities of each development stage in assessing comparability in terms of power to identify differences and assess their relevance to the final clinical outcome gradually accumulated. In addition to the commitment to the biosimilarity approach, it is important to comply with the general requirements applicable to any drugs produced at an industrial scale. Experience showed that the demonstration of biosimilarity based on a range of analytical and functional tests and mainly clinical pharmacological studies is universal and allows extrapolating therapeutic indications. The establishment of biosimilar interchangeability, since the active substance by definition is a version of the active substance of the corresponding reference biological product, can introduce additional difficulties. A single approach to the establishment of biosimilar interchangeability has not yet been developed.