Under European Union (EU) law, the manufacture or import of medicinal products in the European Union is subject to manufacturing or import authorisation. Any company wishing to manufacture a medicinal product must hold a manufacturing authorisation issued by the national competent authority of the Member State where they carry out these activities. To obtain a manufacturing or import authorisation, all medicinal products for human use intended for the European Union market must be produced in accordance with EU Good Manufacturing Practice (GMP) principles and guidelines. GMP is a code of quality standards concerning the manufacture, processing, packing, release and holding of a medicinal product placed within the European Economic Area. GMP describes the minimum standard that a medicines manufacturer must meet in their production and quality control processes, including those involving medicinal products intended for export only and medicines and active substances imported into the EU. GMP is mandatory for all medicinal products that have been granted a marketing authorisation as well as for the manufacture of investigational medicinal products. GMP is also applicable to Advanced Therapy Medicinal Products (ATMPs). However, regarding the level of complexity and the specific characteristics of ATMPs (use of substances of human origin such as blood, tissues and cells), the European Commission has published in accordance with Article 5 of Regulation (EC) No 1394/2007 on ATMPs, Guidelines on GMP specific to ATMPs. These guidelines provide the GMP requirements that should be applied in the manufacturing of ATMPs that have been granted a marketing authorisation and/or used in clinical trial setting.