The purpose of our study was to assess the effect of administration of erythropoietin on postoperative anemia in patients with congenital heart disease who had undergone open heart surgery without the use of homologous blood. One intravenous and one subcutaneous dose of 300 units of erythropoietin per kg body weight was given to 10 patients at a mean of five (3–8) days after surgery. Another group of 10 patients, who had undergone open heart surgery but were not given erythropoietin postoperatively, were used as controls. There was a significant fall in all patients in hemoglobin from 13.6±1.3 gm/dl prior to surgery to 9.8±1.6 gm/dl after surgery. In patients treated with erythropoietin, there was an immediate significant rise in hemoglobin and hematocrit. Hemoglobin rose by 14% on the seventh day after treatment (the twelfth day after surgery) and by 25% on the tenth day after treatment (the fifteenth day after surgery). It had increased by only 8% 15 days after surgery in the controls. These findings suggest a beneficial effect of administration of recombinant erythropoietin on postoperative anemia in children who had undergone open heart surgery without the use of homologous blood.