Cord blood has recently become an alternative to bone marrow transplantation, generating the need for cord blood banks where large numbers of frozen cord blood units can be stored. The Barcelona Cord Blood Bank (bcB) was created in October 1995. Initially, several methods for volume reduction were tested, including Ficoll, Percoll, Gelatin and HES sedimentation. Of these, HES sedimentation (88% +/- 11 CD34+ cells recovery) was the one chosen for routine banking. Up to November 1997, the bank has processed 754 units with a median of 1.05 x 10(9) nucleated cells and 2.5 x 10(6) CD34+ cells stored per unit. Nine of these units have been shipped for transplantation.