The sensitivity and specificity of enzyme immunofiltration and DNA hybridization were compared in human cytomegalovirus (HCMV) (AD 169)-infected MRC-5 cells. The enzyme immunofiltration was carried out on glass fiber filters in microplates, using an HCMV (AD 169) monoclonal antibody and a peroxidase conjugate. The DNA hybridization was carried out with a microfiltration apparatus, using a 32P-labelled HCMV (AD 169) Eco R1 D fragment probe. The sensitivities of enzyme immunofiltration and DNA hybridization were 1.82 X 10(3) and 1.13 X 10(3) infected cells, respectively. Both methods were highly specific, but enzyme immunofiltration was faster and simpler.