We describe incidence, clinical features, serological data, response to therapy and outcome of autoimmune cytopenias (ACs), including autoimmune hemolytic anemia (AIHA) and autoimmune thrombocytopenia (AIT) in a series of 281 consecutive adults with hematological malignancies that received single-unit umbilical cord blood transplantation (UCBT) at a single institution. AIHA was diagnosed in 15 patients at a median time of 181 days (range, 25-543), 12 of them had cold antibodies (IgM). The 3-year cumulative incidence (CI) of AIHA was 5.4% (CI 95% 2.7-8.1). Concomitant infections at the time of AIHA were present in 10 patients. Five out of nine patients that received corticosteroids achieved either a PR or a CR, whereas six out of eight patients that received rituximab responded. Four patients developed AIT giving a 3-year CI of 1.4% (CI 95% 0-2.8), concomitant infections were present in three of them. Multivariable analysis showed that development of chronic GVHD (relative risk (RR) 4; 95% CI 1.1-13.7; P=0.03) and diagnosis of CML (RR 4.3; 95% CI 1.5-12.7; P=0.008) were associated with an increased risk of AC. In conclusion, AIHA and AIT are relevant and clinically significant complications in UCBT recipients, especially among those that develop chronic GVHD. Response to therapy is sub-optimal, and rituximab should be considered as a therapeutic option, in this setting were most patients had cold AIHA and a serological profile similar to that seen in cold agglutinin disease.