Renal dysfunction associated with polyoma BK virus (BKV) reactivation usually occurs in the setting of profound immunosuppression related to renal transplantation and hematopoietic stem cell transplantation. However, it has been rarely described as a complication during the course of conventional chemotherapy. Here, we report a case of BKV-associated acute renal failure developed in a patient suffering from refractory peripheral T-cell lymphoma, not otherwise specified. After repetitive cycles of salvage chemotherapy, the patient developed fever and urinary frequency, rapidly followed by anuria that necessitated the emergent institution of hemodialysis. Cytologic examination of the urine revealed the presence of decoy cells and positive immunostaining for polyomavirus simian virus 40 antigen. High levels of BKV were detected in urine and plasma with quantitative real-time polymerase chain reaction, strongly suggesting that his renal failure was due to polyoma virus-associated nephropathy. This rare complication should be kept in mind in case of unexplained renal failure developed in immunodeficient patients undergoing cytotoxic chemotherapy.