Intravascular fetal transfusion has gained widespread acceptance and has supplanted the use of intraperitoneal fetal transfusion in management of severe alloimmune disease in many centers. This study compares the two methods with regard to multiple objective end points of performance, therapy, and outcome in a highly matched case-control fashion. The intravascular approach is better on almost every level. More surviving infants who are in better condition at a mature gestation and whose mothers have fewer complications and sequelae are the result. Whereas intraperitoneal transfusion should not be abandoned altogether, it is a second-line procedure used only in very limited circumstances. Intravascular fetal transfusion offers realistic prognosis for intact survival at virtually any extreme of alloimmune disease.