Objective: To evaluate the validity of prenatal diagnosis work-up for congenital cytomegalovirus (CMV) in women with primary infection. Methods: Sixty-three pregnant women with primary cytomegalovirus disease (including two with twin pregnancies), referred to three tertiary perinatal centers over 4 years, underwent evaluation for congenital cytomegalovirus. Fetal diagnosis was made after 21 weeks’ gestation by amniocentesis and fetal blood sampling (40 subjects), or amniocentesis only (23 subjects). Results: Twenty-two (35%) pregnancies showed evidence of vertical transmission: 13 of them underwent funipuncture, but only ten (77%) of the 13 showed positive immunoglobulin (Ig)-M results in fetal blood. No cases of positive fetal serum Ig-M with negative amniotic fluid culture or polymerase chain reaction were observed. In nine (41%) of the 22 pregnancies with evidence of vertical transmission, abnormal ultrasonographic findings were recorded. Six (27%) women with evidence of vertical transmission continued their pregnancies and in only one (with prenatal ultrasonographic abnormalities) was an infant born with neurologic sequelae. In 41 (65%) pregnancies, no evidence of vertical transmission was found, and 37 continued to term. Only one newborn from this subgroup subsequently showed mild motor disability during a median of 23 months of follow-up. Conclusion: Among pregnant patients with primary CMV infection, analysis of amniotic fluid detected all of the infected fetuses. Thus, this is a reliable tool for counseling pregnant women with primary infection. This may guide the patient as to whether or not pregnancy can be continued with a high level of confidence.