Enzyme ImmunoAssay (ELISA) for the quantitative/qualitative determination of IgG antibodies to Cytomegalovirus in plasma and sera. For “in vitro” diagnostic use only. Microplates are coated with native Cytomegalovirus antigens, highly purified by sucrose gradient centrifugation and inactivated. The solid phase is first treated with the diluted sample and IgG to Cytomegalovirus are captured, if present, by the antigens. After washing out all the other components of the sample, in the 2nd incubation bound anti Cytomegalovirus IgG are detected by the addition of polyclonal specific anti hIgG antibodies, labelled with peroxidase (HRP). The enzyme captured on the solid phase, acting on the substrate/chromogen mixture, generates an optical signal that is proportional to the amount of anti Cytomegalovirus IgG antibodies present in the sample. A Calibration Curve, calibrated against the1st W.H.O international standard , makes possible a quantitative determination of the IgG antibody in the patient.