The development of an iatrogenic vascular lesion, such a renal pseudoaneurysm or arteriovenous fistula, is a rare complication of partial nephrectomy. These lesions should be considered in patients presenting with an enhancing mass in the resection bed shortly following partial nephrectomy. Early timing following surgery, large relative size, and the presence of recurrent hematuria suggest the diagnosis of an iatrogenic vascular lesion. Duplex ultrasound is a useful non-invasive imaging modality for differentiating these lesions from a local tumor recurrence.