We report a case of cold hemagglutinin disease associated with Mycoplasma pneumoniae infec tion treated with cord blood transfusion. Cold hemagglutinin disease is a hemolytic anemia most
commonly associated with cold-reactive autoantibody with anti-I specificity. On the basis of the fact
that the level of I antigen on cord red blood cells is extremely low, a six year old male patient was
transfused with 60 mL of ABO blood type-matched, cord blood. No complication from the transfu sion was observed. Due to the deficiency in cord blood supply, filtered irradiated RBC 100 mL was
transfused three times thereafter. The hemoglobin level began to increase from the fifth hospital
day. The patient was discharged without additional transfusion on the eleventh hospital day. No
remarkable complications were noted at the time of discharge.