BK virus associated nephropathy (BKVN) can cause clinically significant viral infections in renal transplant recipients, leading to allograft dysfunction and loss. The usual management of BKVN involves reduction of immunosuppression and the addition of leflunomide, quinolones, and cidofovir, but the rate of graft loss remains high. The aim of this study was to assess the impact of treatment with intravenous immunoglobulin (IVIG) on the outcome of BKVN in renal transplant recipients. Upon diagnosis of BKVN, patients remained on anti-polyomavirus treatment consisting of reduction of immunosuppression and the use of leflunomide therapy. Treatment with IVIG was given only to patients who did not respond to 8 weeks of the adjustment of immunosuppression and leflunomide. All 30 patients had persistent BK viremia and BKVN with their mean BK viral loads higher than the baseline (range 15,000 - 2 millions copies/mL). Mean peak BK load was 205,314 copies/mL compared to 697 copies/mL after one year follow-up. Twenty-seven patients (90%) had positive responses in clearing viremia. The actuarial patient and graft survival rates after 12 months were 100% and 96.7%, respectively. IVIG administration appeared to be safe and effective in treating BK viremia and BKVN and in preventing graft loss in patients who had inadequate response to immunosuppression reduction and leflunomide therapy.