This 1-day workshop showed that the infectivity of B19 DNA in donor blood and the neutralizing action of different antibodies present in the donated blood are not yet fully understood. It is possible that B19-induced anemia and reticulocytopenia are not being recognized in transfused recipients other than those in specific risk groups. The testing of blood components for any infectious agent is usually clinically driven, and, if B19 NAT were recommended at the present time in other than plasma products, a CMV-like model might prove appropriate; that is, virus screening would be performed on blood components destined for high-risk groups only. Currently, there is insufficient evidence to recommend universal testing, especially for single units. Workshop participants recommended that basic research continue in the scientific areas addressed. If clinical trials were to be developed, participants recommended that they include special risk groups such as seronegative pregnant women and children with malignancies who are receiving chemotherapy.