id="p0010">We studied predictive factors for lymphocyte recovery after single umbilical cord blood transplantation.
id="p0015">We analyzed the impact on outcomes of absolute lymphocyte count on day 42 after single umbilical cord blood transplantation.
id="p0020">We report 3 different factors influencing lymphocyte recovery after cord blood transplantation: infused CD3+ cell counts, ATG dose, and HLA mismatch degree.
id="p0025">We found an association between higher ALC42 level and improved nonrelapse mortality and survival.
id="p0030">Infusion of a high number of CD3+ cells, administration of low ATG dose in conditioning regimens, and the use of better HLA-matched CBUs may help improve outcomes after umbilical cord blood transplantation.