Background: Cytomegalovirus infection, in renal transplant recipient, are the major cause of morbidity, mortality, and are the leading cause of organ rejection. Objective: The aim of work was to compare the sensitivity of CMV antigenemia assay to that of plasma PCR in renal transplant patients. Subject and methods: Thirty renal transplant recipients were subjected to full clinical history, amplicor CMV test (a qualitative plasma PCR), PP65 antigenemia assay, and anti-CMV/IgM. Results: (1) The sensitivity of plasma PCR was superior to that of antigenemia assay and anti-CMV/IgM (the rate of detection being 73.3%, 66.7% and 36.7%). (2) Antigenemia assay was the most sensitive test in detection of positive cases (94%) with CMV disease, whereas plasma PCR was the most sensitive test in detection of positive cases (76.4%) with active CMV infection. (3) There is close relation between acute rejection episodes and CMV infection. Conclusion: Antigenemia assay could be used for monitoring of patients with CMV disease whereas plasma PCR could be used for early detection of active CMV infection. Both tests proved to be more sensitive and valuable than anti-CMV/IgM.