Polyomavirus BK has emerged as an important complication after kidney transplantation. Although, BK nephropathy develops in only 1% to 10% of renal transplant recipients, its prognosis when present is very poor. The relationship of urine cytokines with Polyomavirus BK viruria after kidney transplantation has not yet been studied and literature reports on cytokine and post­transplant BK viruria are rare. In a prospective study, we compared posttransplant urine cytokine levels of 40 outpatient renal transplant recipients without BK (n = 20), with low-level (2.6-5.0 log10) (n = 12) and high-level (5.1-9.8 log10) (n = 8) viruria and 20 healthy controls (HCs). S (soluble) IL-1RA (interleukin-1 receptor 2antagonist), IL-2, sIL-2R, IL-3, IL-4, IL-6, sIL-6R, IL-8, IL-10, IL-17, TGF (tumor necrosis), and INF- (interferon-) TGF-&#946;2 (transforming growth factor-&#946;2), levels were determined using commercially available ELISA kits. Urine proinflammatory cytokines IL-6 (p = 0.015) and sIL-6R (p = <0.001) were significantly higher in BK+ than in BK- patients. Interestingly urine sIL-6R (p = <0.001) was lower in BK- patients than in HCs, whereas BK+ patients had significantly higher urine IL-6 (p = <0.001) than HCs. Urine levels of all cytokines were similar in patients with high and low level BK viruria (p = n.s.), whereas patients with high and low level viruria had higher urine sIL-6R (p = 0.003 and p = 0.004 respectively) than patients without viruria. In conclusion, Renal transplant recipients with BK viruria have a strong inflammatory cytokine response with activation of IL-6 and sIL-6R, which might be involve in pathogenesis of Polyoma BK virus-associated nephropathy. Our data suggest that the inflammatory response is heightened in kidney during BK virus replication independent to virus load.