Gross hematuria, graft pain, and rising serum creatinine are classic signs of acute rejection, obstruction, or bacterial pyelonephritis for patients with renal transplants. This presentation often prompts percutaneous renal allograft biopsy. If subsequent evaluation fails to show evidence of acute rejection, obstruction, or bacterial infection, viral etiologies should be considered. We report a 14-year-old Hispanic female with a living-related renal transplant who had gross hematuria, graft tenderness, and increased serum creatinine, but did not have evidence of acute rejection, obstruction, or bacterial pyelonephritis. To our knowledge, this is the first report of adenovirus pyelonephritis in a transplanted kidney of a pediatric patient, with isolation of adenovirus in the urine and in the allograft using immunocytochemical techniques.