Direct intravascular transfusion of the fetus with Rhesus isoimmunization is becoming more widespread as the procedure of choice in the treatment of this disease. To date no direct complications of this new procedure have been reported. The authors describe a case of cord hematoma with resulting fetal compromise secondary to venipuncture of the umbilical vein. Doppler studies and review of the fetal heart rate tracings pointed toward umbilical artery vasospasm secondary to the cord hematoma as the etiology of the transient fetal bradycardia.