The kinetics of human cytomegalovirus (HCMV)-specific immunoglobulin E (IgE), M (IgM), A (IgA) and G (IgG) were studied in 421 sera obtained from 19 renal allograft recipients by enzyme-linked immunosorbent assay (ELISA). Cytomegalic inclusion disease (CID) occurred in 11 (57.9%) patients. HCMV infection was diagnosed in all (100%) of these patients by testing for specific IgE. In contrast, increased levels of IgM and IgA class antibody against HCMV were detected in only 45.5% and 18.2% patients suffering from primary or recurrent HCMV infection, respectively. Concerning the time interval between the onset of clinical symptoms and the first positive test, no significant differences in the kinetics of HCMV-specific immunoglobulins E, M, A and G were observed. Elevated specific IgE levels persisted for longer time intervals than the other immunoglobulin classes. As shown by the present study, specific IgE proved to be a more reliable serologic marker than IgM and IgA for the serologic detection of HCMV infection in renal allograft recipients.