An extraordinary meeting of the International Working Group on the Standardization of Genome Amplification Techniques for the safety testing of blood, tissues and organs for blood borne pathogens was held on 2 March 2007, at the National Institute for Biological Standards and Control. The aim of the meeting was to investigate ways to harmonize results obtained for the detection and quantification of different genotypes of parvovirus B19 (B19V) DNA by control laboratories and manufacturers of plasma derivatives. The meeting explored issues of B19V such as the classification of B19V strains, the prevalence and distribution of different genotypes, the clinical and biological significance of different genotypes, the detection of different genotypes in plasma-derived products, and their susceptibility to virus-inactivation procedures. At this meeting and through subsequent studies, high titre, high volume samples have been identified representing different genotypes of B19V, which will be evaluated by collaborative study to prepare reference panels for the purposes of assay validation.