Objective:To discover the matter of active Cytomegalovirus (CMV) infection before renal transplantation and its affection on the patients after transplantation. Methods:the numbers of pp65 positive cells in peripheral blood in 32 normal persons who were used as control and 156 uremia patients before renal transplantation were determined between June 1

2006 and November 30

2008. The variations of number of pp65 positive cells in peripheral blood in patients after renal transplantation were investgated. Results: In control group the number of pp65 positive cells in peripheral blood was 0/5×104 WBC. Before renal transplantation there was 12.2 percent of uremia patients whose pp65 positive cell counting was more than 0 cell /5×104 WBC.In this kind of patient the case number of serious active CMV infection(pp65 positive cell counting was more than 100 cells /5×104 WBC) and CMV disease after renal transplantation was more than others.The difference was significant. Conclusions: The findings suggest that active CMV infection before renal transplantation is an important sake that causes serious active CMV infection and even CMV disease after renal transplantation.