Parvovirus B19 is the only member of the Parvoviridae family known to cause disease in humans. Owing to the high level of cell tropism the virus can only replicate in proliferating and differentiating erythroid precursor cells, which are present in human bone marrow and foetal liver. As human bone marrow is very difficult to obtain, an alternative in vitro system for the propagation of B19 virus has been developed, based on the application of mobilized haemapoietic progenitor (apheresis) cells. These cells are routinely harvested from cancer patients after treatment with recombinant human granulocyte/macrophage colony-stimulating factor. Replication of parvovirus B19 in vitro is possible in these cells after stimulation with erythropoietin. Therefore, this system is an easily, accessible alternative to the use of human bone marrow in parvovirus B19 infection assays.