The London Cord Blood Bank was established with the aim of collecting, processing and storing 10000 unrelated stem cell donations for the significant number of children in the UK requiring transplantation, for whom a matched unrelated bone marrow donor cannot be found. Collection is performed at two hospitals by dedicated cord blood bank staff after delivery of the placenta. Mothers are interviewed regarding medical, ethnic and behavioural history by nurse counsellors and sign a detailed consent form. Donations are returned to the bank for processing. Volume reduction is undertaken by a simple, closed, semi-automated blood processing system, with excellent recovery of progenitor cells. Units are cryopreserved and stored in the vapour phase of liquid nitrogen. Blood samples from mothers and cord blood donations are tested for the UK mandatory red cell and microbiology markers for blood donors. Donations are typed for HLA-A, B and DR at medium resolution (antigen split) level using sequence-specific oligonucleotide probing and sequence-specific priming techniques. The selection of collection hospitals on the basis of ethnic mix has proven effective, with 41.5% of donations derived from non-European caucasoid donors. Bacterial contamination of collections has been dramatically reduced by implementation of improved umbilical cord decontamination protocols.