Patients with renal transplant received immunosuppressive drugs are prone to any opportunistic infections such as CMV. CMV activity occurs in patients who have IgG anti CMV and causes sever disease with high mortality and transplant rejection. This study is planed to detect the prevalence of anti CMV (IgM, IgG) before transplantation and long term follow up of active CMV disease incidence. In this cross sectional study, 70 patients candidate for renal transplantation studied in Alzahra Hospital Of Isfahan. After blood sampling and filling questionnaires, ELISA test for anti CMV (IgM,IgG) performed and prevalence of these antibodies calculated. Prevalence of these antibodies calculated according to age and gender and long term follow up was done for incidence of acute CMV infection following transplantation. 70 patients studied among them 64 (91/4%) had IgG-anti CMV. There was 38 male (59/3%) and 26 female (40/6%). 2 person had IgM-anti CMV that both of them were female (100%). There was relationship between anti CMV-IgG prevalence and age (p<0/05) and no relationship of anti-CMV IgG and gender. There was no any relationship of anti CMV-IgM and age/gender. 2 cases (2/8%) of active CMV disease occurred during six months after transplantation and one of them rejected the transplant. According to the prevalence of anti CMV-IgG among studied patients here was high risk of re infection which causing sever complication and transplant rejection so this recommendable to prevent sever infection and mortality by performing CMV serology before transplant ,detecting antigenemia (PP) and PCR weekly as a screening test.