BACKGROUND: Umbilical cord blood is a useful stem cell source for some patients. The American Red Cross Cord Blood Program was established as a national network of cord blood banks. Nine thousand cord blood units were cryopreserved for transplant use. STUDY DESIGN AND METHODS: This report summarizes the experience with the first 125 cord blood units that have been distributed for transplant for 122 patients at 36 different transplant centers worldwide. Patients were treated with a variety of conditioning regimens. RESULTS: Most patients had acute myelogeneous leukemia (21%), genetic disorders (22%), or acute lymphoblastic leukemia (18%). The median age of the patients was 11 years with a range of 2 months to 63 years. The patients ranged in size from 3 to 120 kg (median, 39 kg). The median number of days to neutrophil engraftment was 22, and the median number of days to platelet engraftment was 63. Thirty percent of patients experienced Grades III to IV acute graft-versus-host disease (GVHD). Survival at 1 year after transplant was 35 percent, with recurrent disease the major cause of death. In multivariate analysis, only age less than 18 years was a significant predictor for improved survival. Forty-two percent of patients were non-Caucasian. Engraftment, GVHD, survival, and disease-free survival were similar among Caucasian and non-Caucasian patients. CONCLUSION: Umbilical cord blood serves as a satisfactory stem cell source for a diverse group of pediatric and adult patients.