A 26-year-old female with Beta-thalassemia/sickle cell anemia was admitted to the hospital with symptoms of a painful crisis. During the next 4 days her hematocrit decreased to 13 percent, and there was reticulocytopenia. She was transfused with four units of red blood cells that were microscopically incompatible, and the hematocrit increased to 29 percent. Eight days later the patient was readmitted with back pain, hemoglobinuria, and a hematocrit of 27 percent. Anti-E, -c, -Jka, and -Yta were identified. The direct antiglobulin test was positive, and the eluate contained anti-c and -Jka. The patient's hematocrit continued to decrease to 14 percent. Transfusions were withheld and the patient recovered uneventfully. Separate 51Cr red blood cell survival studies showed significantly shortened survival of both autologous and R(1)R(1), Jk(a-), Yt(a+) erythrocytes. This case illustrates the complexity of transfusion management in hemoglobinopathy patients.