The aims of the present study were to assess the incidence of cytomegalovirus (CMV) reactivation, and to determine the predictive factors for CMV reactivation in CMV seropositive kidney-transplant patients. One hundred ninety CMV seropositive kidney-transplant patients were included in this study; of these, 39 patients had received CMV prophylaxis. CMV DNAemia was assessed by real-timepolymerase chain reaction assay every 2 weeks until day 120, then every 3-4 weeks until day 180, and then every month until day 365. One hundred seven patients (56.3%) had at least one positive CMV DNAemia within the first year. The time between renal transplantation and the first positive CMV DNAemia was 59 +/- 5 days. The number of positive CMV DNAemia/patient was 3.28 +/- 0.22. CMV viral load at first positive CMV DNAemia was 704 (10-742,000) copies/ml. The donor CMV seropositivity, the absence of CMV prophylaxis, and the occurrence of acute rejection before CMV reactivation were independent factors associated with CMV reactivation within the first year after kidney transplantation. Hence, CMV reactivation is frequent after kidney transplantation. CMV prophylaxis in CMV seropositive kidney-transplant patients should be offered to avoid CMV-related side-effects.