Benefits of two parallel phase II trials of transplantation of unrelated umbilical cord blood or bone marrow from HLA-haploidentical relatives supplied equipoise for direct comparison of these donor sources. Amongst June 2012 and June 2018, 368 sufferers aged 18-70 years with chemotherapy-sensitive lymphoma or acute leukemia in remission had been randomly assigned to undergo cord blood (n=186) or haploidentical (n=182) transplant. Decreased intensity conditioning comprised total physique irradiation with cyclophosphamide and fludarabine for each donor sorts. Graft-versus-host illness prophylaxis for cord blood transplantation was cyclosporine and mycophenolate mofetil and for haploidentical transplantation, post‐transplant cyclophosphamide, tacrolimus and mycophenolate mofetil. The main endpoint was two-year progression-free of charge survival. Therapy groups had comparable age, sex, self-reported ethnic origin, efficiency status, illness and illness status at randomization. Two-year progression-free of charge survival was 35% (95% CI, 28-42%) compared to 41% (95% CI, 34-48%) following cord blood and haploidentical transplants, respectively (p=.41). Pre-specified evaluation of secondary endpoints recorded greater two-year non-relapse mortality following cord blood, 18% (95% CI, 13-24%) compared to haploidentical transplantation, 11% (95% CI, six-16%), p=.04. This led to reduced two-year all round survival following cord blood compared to haploidentical transplantation, 46% (95% CI, 38-53) and 57% (95% CI 49-64%), respectively (p=.04). The trial did not demonstrate a statistically substantial distinction in the main endpoint, two-year progression-free of charge survival, among the donor sources. Although each donor sources extend access to lowered intensity transplantation, analyses of secondary endpoints, which includes all round survival, favor haploidentical bone marrow donors. (Funded by the National Heart, Lung, and Blood Institute-National Cancer Institute ClinicalTrials.gov quantity, NCT01597778).