Objective: To assess the role of urine cytology as a simple and noninvasive tool in assessment of post renal transplant polyoma virus infection Case Report: Polyoma virus BK can infect the renal transplant patients on immunosuppressive therapy resulting in progressive renal allograft dysfunction and graft loss. We report a case of 42 year old male who underwent renal transplant six weeks ago followed by immunotherapy, had signs of rejection in the immediate post- transplant period for which he was put on antithymocyte globulin. He now presented with dysuria and urine cytology was done. Viral cytopathic effect in the form of enlarged nucleus with basophilic viral intranuclear inclusions and ground glass chromatin known as __ampersandsignldquo;decoy cells__ampersandsignrdquo; were seen. Conclusion: Urine cytology can be used as a simple and cost effective screening method for monitoring the renal transplant patients for polyoma virus allograft nephropathy