Cord blood transplantation has been proven to be a suitable form of treatment for a variety of diseases in childhood and more recently in an increasing number of adult patients. Banks of cord blood cryopreserved after HLA testing are required in order to provide various HLA types for unrelated transplantation. To optimize storage space cord blood needs to be stored as a separated product. Several early methods of cord blood separation resulted in a significant loss of progenitor cells. We used a separation procedure where the donation was separated by centrifugation into a buffy coat fraction, a red cell fraction, and a plasma fraction. Twenty-five samples, (mean initial volume 81 ml) were assessed. Nucleated cells were recovered in the buffy coat fraction. Recoveries of nucleated cell count, total progenitors and CD34-positive cells in the buffy coat were 90%, 88% and 100%, respectively. The buffy fraction was tested for sterility by aerobic and anaerobic culture. Using this closed bag system, volume reduction was achieved while maintaining sterility and retaining progenitor cells in a final mean buffy coat volume of 44 ml. Red cell and plasma fractions were available for ABO grouping, virology testing and cryopreservation. The results show that cord blood can be effectively volume-reduced using simple and readily available blood banking techniques.