Viral safety of blood donations, plasma products, viral vaccines and gene therapy medicinal products, biotechnical-derived products and tissue and cell therapy products is a particular challenge. These products are manufactured using a variety of human or animal-derived starting materials and reagents; therefore, extensive testing of donors and of cell banks established for production is required. Furthermore, the viral safety of reagents, such as bovine sera, porcine trypsin and human transferrin or albumin needs to be considered. Whenever possible, manufacturing steps for inactivation or removal of viruses should be introduced; however, sometimes it is not possible to introduce such steps for tissues or cell-based medicinal products as the activity and viability of cells will be compromised. It might be possible to implement steps for inactivation or removal of potential contaminating enveloped viruses only for production of small and stable non-enveloped viral gene vectors.