The aim of this meta-analysis is to compare the HLA disparities and the outcome of UCBT, i.e. the disease-free survival (DFS), engraftment, graft-versus-host disease, (GVHD), and transplantation related mortality (TRM).We electronically searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Pubmed, IBMTR and critically appraised all relevant articles (1989.01–2008.12). Comparative studies are carried on HLA typing and cord blood transplantation with research on stem cells engraftment, GVHD, TRM, and DFS. A meta-analysis is performed using Review Manager 5.0 software and adopted funnel plot regression assessed the publication bias.We got 882 records, and 10 trials totaling 1589 patients assessed. Pooled comparisons of studies of outcomes found that the incidence of neutrophil and platelet engraftment failure increased with HLA-mismatched antigen increased, ≥2-Ag mismatched group had a higher risk of ≥II degree GVHD and a lower DFS rate than the HLA matched group.Our meta-analysis confirmed that with the HLA-mismatched antigen increased, the rate of graft failure, severe GVHD and TRM increased, and the DFS decreased. We cannot fully exclude the possibility of center biases in treatment and selection of patients and well-designed trials need to carry out.