Umbilical cord blood (CB) has been rapidly established as an alternative source of stem cells to bone marrow for allogeneic-related and unrelated hematopoietic transplantation. To date, almost 70 000 CB units are available for transplantation and more than 2000 CB transplants (CBT) have been performed, mostly in children, for the treatment of a variety of malignant and nonmalignant conditions. Considerable experience has been rapidly accumulated in this field and many aspects of CBT have been elucidated, while other questions remain unresolved. A concise review of the clinical results achieved after related and unrelated CBT is presented and discussed.