The presence of human cytomegalovirus (HCMV) genome in spleen tissue was studied by using DNA hybridization techniques in seropositive and seronegative organ donors without clinical or laboratory confirmed HCMV infection. The serum samples of these patients were screened by latex agglutination test (LA) and enzyme linked immuno sorbent assay (ELISA) for the presence of HCMV antibodies, and confirmed by immunoblotting technique (IB ). For the detection of HCMV sequences in spleen tissue dot blot DNA hybridization (DBH) using probes derived from immediate-early and late regions (ES and BH fragment respectively) of the HCMV genome were used. Samples positive in DBH were further tested by in situ DNA hybridization (ISH) using the ES probe. The number of spleen tissue specimens positive for HCMV nucleic acids indicated that HCMV may be present in human beings, even without serological evidence.Human cytomegalovirus (HCMV), a member of the herpesvirus family, is an ubiquitous human viral pathogen. Infection with HCMV is usually asymptomatic in the immunocompetent host, but can result in a dramatic disease in immunosuppressed patients [15]. After primary infection the virus persists in the host as a chronic or latent infection, which can periodically reactivate to an active infection. HCMV is known to be transmitted through blood transfusions [1,24] and transplanted organs [10,33] which can result in a severe HCMV disease, especially in immunosuppressed and seronegative patients [3,22]. Several studies indicate that in HCMV seropositive healthy individuals latent infection can be demonstrated by the presence of HCMV antigens. This is done by immunohistochemical techniques or by the detecting the presence of Offprint requests to: Y. J. Kraat,