Except for renal transplant recipients, glomerulonephritis has only very rarely been associated with renal cytomegalovirus (CMV) infection. The kidneys of five infants with congenital cytomegalic inclusion disease, including renal infection, were examined at autopsy. Two of the infants had glomerulonephritis. The younger, a 4-month-old female, had diffuse proliferative and necrotizing glomerulonephritis; virus was present in nuclei and cytoplasm of glomerular endothelial cells and, possibly, in leukocytes as well. There were no electron-dense deposits. The other infant, a 5-month-old male, had diffuse mesangial and focal segmental proliferative and sclerosing glomerulonephritis; electron-dense mesangial deposits were seen ultrastructurally. Three additional infants (a newborn male, a 2-day-old male, a 6-week-old female), all with CMV in tubules and one with a single glomerular inclusion, had only rare glomerular abnormalities, i.e., mesangial proliferation in less than 10 per cent of glomeruli (one infant) and segmental sclerosis in less than 1 per cent of glomeruli (all three infants). Thus, congenital renal CMV infection was associated with proliferative glomerulonephritis in the two infants who survived the longest. The three with shorter survival times had only minor glomerular alterations.