Inflammatory myofibroblastic tumor is a reactive proliferative lesion that occurs extremely rarely in the renal pelvis, especially during childhood. We report 1 such case that occurred in a child who presented with prolonged fever and abdominal pain. Ultrasonography and abdominal computed tomography revealed a left renal pelvic mass. She received conservative surgical treatment. The diagnosis was confirmed by pathological and immunohistochemical studies. Distinguishing inflammatory myofibroblastic tumor from other malignant renal pelvic tumors in children is essential to preventing unnecessary nephrectomy.