As in adults, renal abscess in children mimicks a tumoral syndrome. Renal abscess, although infrequent, should however be kept in mind because it is important to make an early diagnosis. The reason is simply that the treatment fo the two conditions is so different. Furthermore, an early accurate diagnosis avoids unnecessary investigations, such as arteriography, as well as unnecessary surgery. Four cases are reported in which the diagnosis of abscess was obtained by correlating both clinical and radiological findings. In only one case was arteriography performed and this was after treatment and it was normal. For an early diagnosis intravenous urography is of paramount importance. It shows a tumoral radiological pattern; in the context of clinical signs of suppuration (high fever, high leucocyte count and variably a urinary tract infection). The radiological findings suggest the diagnosis of abscess. On treatment the rapid regression and disappearance of the various clinical, laboratory, and radiological findings confirms the diagnosis of renal abscess.