An 18-month-old girl with hereditary spherocytosis underwent closure of the ventricular septal defect, commissurotomy of the pulmonary valve, and patch angioplasty of the pulmonary trunk without previous splenectomy. No serious complications as a result of hemolysis occurred in the perioperative period. Open heart surgery can therefore be safely performed in young children with congenital heart disease and hereditary spherocytosis who have not previously undergone splenectomy.