Cytomegalovirus (CMV) has been shown to be an important pathogen in liver transplant recipients. The presence of primary infection and the use of OKT3 monoclonal antibodies appear to be risk factors for symptomatic infection. In my experience, the disease is clinically similar to the CMV disease seen in other transplant groups except that infection of the liver may be clinically more important in liver recipients than in other transplant recipients. Various regimens for prevention of CMV infection in transplant recipients have been investigated, including vaccination, prophylaxis with a variety of polyclonal immunoglobulin preparations, the use of immunomodulators such as interferon-alpha, and antiviral prophylaxis with acyclovir. These studies have been performed in kidney or bone marrow recipients and may not be applicable to liver recipients. Studies in progress on which no data are currently available employ human monoclonal immunoglobulin and ganciclovir. It is not possible at present to make any specific recommendations for prophylaxis. It is likely that ongoing randomized studies and further understanding of host-virus interactions in CMV disease will lead to useful prophylactic regimens in this group of patients.