The results for 49 patients with hematologic and non malignancies who were subjected to a cord blood transplantation from HLA-mismatched unrelated donors (UCBT) are presented here. This retrospective study included 22 patients with acute lymphoblastic leukemia, 12 with acute myelogenous leukemia, one each with chronic myelogenous leukemia, refractory anemia with myelodysplastic syndrome, and juvenile myelomonocytic leukemia, three with Wistott-Aldrich syndrome, three with adrenoleukodystrophy, two with Hunter's syndrome, one each with Hurler's syndrome, purine nucleotide phosphorylase deficiency, pure red cell aplasia, and severe aplastic anemia. In malignant diseases, the Kaplan-Meier estimates for three-year overall survival (OAS) and event-free survival (EFS) were 51.9 +/- 17.8, and 51.4 +/- 17.8%, respectively. In patients with non malignant disease, the Kaplan-Meier estimates for three-year OAS and EFS were 64.2 +/- 28.8, and 37.5 +/- 29.4%, respectively. In patients with malignancy, the HLA disparity had no effect on OAS, EFS, incidence of acute graft-versus-host disease, or engraftment. On the other hand, for engraftment, the use of UCBT from HLA-mismatched unrelated donors may require a larger study in patients with non-malignant diseases.