Introduction: Nephropathy from BK virus (BKV) infection is an evolving challenge in kidney transplant recipients. It is the consequence of modern potent immunosuppression aimed at reducing acute rejection and improving allograft survival. Untreated BKV infections lead to kidney allograft dysfunction or loss. Decreased immunosuppression is the principle treatment but predisposes to acute and chronic rejection. Screening protocols for early detection and prevention of symptomatic BKV nephropathy have improvedoutcomes. It has been recommended that screening for BKV should be performed every 3 months for the first 2 years following transplantation.Methods: In a prospective, two-center study, we followed 40 renal transplant recipients who were receiving immunosuppressive therapy that included CSA, Mycophenolate Mofetil, and Prednisolon.Plasma BKV DNA was measured 3, 6, 12, 18, and 24 months after transplantation and whenever serum creatinine increased or kidney biopsy was indicated. The viral load in plasma was quantified with the use of a real-time polymerase chain reaction method. Renal biopsy was performed if allograft function deteriorated.Results: The subjects were 20 to 62 years old. The mean age was 40.80 ± 13.53 included 22 males and 18 females. They were followed 6 to 24 months (mean duration was 13.84 ± 5.79 months). Five (12.5%) cases received ATG because of delayed graft function or rejection, from 126 sPCR tests that was done during follow up, 57 cases (45%) were positive and 69 ones (55%) were negative. PCR test was negative during period of follow up only in 4 (10%) cases. Among positive PCR tests, viral load was less than 100 copy/mL in 41 (72%), 100 to 1000 copy/mL in 13 (23%), and 1000 to 2000 copy/ mL in 3 (5%) cases. The last serum creatinine was 1.08 ± 0.36. There were no significant differences in serum creatinine level between above-mentioned groups. There were no cases with biopsy-proven BKV nephropathy or significant BK replication (plasma DNA-PCR load more than 10000 copy/mL that is presumptive of BKV nephropathy). Despite this situation, we decreased immunosupressive drug (Mycophenolate Mofetil) in 2 cases with BKV viral load>1000 copy/mL for prevention of BKV nephropaty.Conclusions: Among renal transplant recipients, a positive BKV DNA-PCR is common but viral load is usually less than 1000 or even 100 copy/mL.The significant viral load (10000 copy/mL) that indicates BKV nephropathy was not a common finding in our study.