The various mechanisms that contribute to the viral safety of therapeutics prepared from human blood plasma are examined. The basic principles behind the 2 most important mechanisms for viral safety, inactivation, and removal are discussed, together with the main issues linked to manufacturing. Validation of virus safety and protein integrity is considered. Currently available methods for inactivetion and removal of viruses are reviewed, followed by an overview of new and experimental methods that may have some promise for the future. This review ends with a brief discussion of the impact fractionation pool size may have on product safety and the potential new threat presented by contamination with prions. Copyright (C) 2001 by W.B. Saunders Company.