Eurocord Transplant has established a registry for studying results of cord blood transplant. We have analyzed 78 patients who have received a related CBT between October 1988 and December 1996. The median follow-up time was 29 months (1-99). The median age was 5 years (0.2-20), median weight 19 kg (5-50). Forty-six patients had a malignant disease: 32 acute leukemia (AL), six chronic myeloid leukemia (CML), four myelodysplastic syndrome, two neuroblastoma and two non-Hodgkin lymphoma. Thirty-two patients were transplanted for non-malignant diseases including 17 bone marrow failure syndromes (BMFS), three sickle cell anemia, five thalassemia and seven inborn errors. The donor was an HLA-identical sibling in 60 cases and an HLA-mismatched donor in 18 cases. As conditioning, 36 patients received irradiation and 40 patients received associated busulfan-containing regimens. GVHD prophylaxis consisted of CsA alone in 36 cases, CsA associated with prednisone in eight cases, CsA, methotrexate (Mtx) with or without prednisone in 28 cases and CsA with monoclonal antibody or ATG in four cases. The median number of nucleated cells (NC) infused/kg was 3.9 x 10(7) (0.7-15). One-year survival was 63 +/- 6%. Age, weight, HLA identity and negative cytomegalovirus (CMV) serology in the recipient were significant favorable prognostic factors. Among these 78 patients, the incidence of grade > or = II GVHD was 9% in HLA-matched CBT and 50% in mismatched CBT (P < 0.001). Neutrophil engraftment was associated with age <6 years (P = 0.02) and weight <20 kg (P = 0.02). It was 73% in patients receiving <3.7 x 10(7) nucleated cells (NC) infused/kg and 85% in patients receiving more (P = 0.06). Favorable factors for platelets engraftment were age <6 years (P = 0.03), weight <20 kg (P = 0.002) and HLA identity (P < 0.0001). Related cord blood transplantation offers a good alternative to BMT. Theses results are in favor of freezing cord blood in families in whom a transplant might be indicated.