Twenty-five percent of cytomegalovirus (CMV)-infected fetuses had sequelae and 8% of those in the recurrent-infected group had sequelae. There is no report yet on the fetal therapy for CMV infections. A Japanese pregnant woman with intrauterine fetal CMV infection diagnosed at 26 weeks of pregnancy is presented. CMV culture of amniotic fluid was positive. A CMV DNA assay using the polymerase chain reaction method of the cord blood and the amniotic fluid was positive during the pregnancy; however, testing for fetal serum CMV-specific IgM was negative. The CMV IgG titer of fetal serum at 27 weeks of pregnancy was a third of that of the maternal serum. CMV hyperimmunoglobulin was injected into the fetal abdominal cavity at 28 and 29 weeks of pregnancy. A second administration of CMV hyperimmunoglobulin increased the titer of CMV IgG in the fetal circulation. At birth, the urine culture was positive for CMV. However, CMV DNA of the ascites became negative. A brain CT scan performed 2 weeks after birth revealed some small calcifications beside the right ventricle. CMV hyperimmunoglobulin injection to the fetal abdominal cavity has been shown to increase the IgG in the fetal serum. This is the first report of fetal therapy of congenital CMV infection.