Human cytomegalovirus (HCMV)-specific antibodies were assayed in cord serum and the respective maternal serum from two groups of newborn infants with congenital HCMV infection. One group of infants exhibited clinically apparent infection with multiple organ system involvement, whereas the second group had subclinical infections. Levels of virus-specific IgG antibodies reactive with several virus-encoded proteins including those reactive with the major envelope glycoprotein complex were significantly higher in cord serum and maternal delivery serum from the group of infants with clinically apparent infection than in serum from those with subclinical infection. Maternal delivery serum from the group with subclinical infection had significantly higher levels of IgM virus-binding antibody and lower levels of IgG virus-binding antibody than did the respective serum from the group with clinically apparent infection, suggesting maternal acquisition occurred later in gestation in the group with subclinical infection. These results suggested that deficiencies in the HCMV-specific antibody response were not associated with clinically apparent congenital infection and that other factors, such as early virus acquisition during pregnancy, might contribute to the severity of intrauterine HCMV infection. © 1990 by The University of Chicago. All rights reserved.