Patients with an accessory kidney are characterized by an excessive number of kidneys. The ureter of theaccessory kidney either drains separately into the bladder or merges with the ureter of the main kidney. Inour case, interestingly, the ureter of the left main kidney drained directly into the accessory kidney and theureter of the latter was the common drainage route for both. The drainage of a normal kidney via the ureterof an accessory kidney has not been reported in the literature, so far. The aim of this report is to presentthe case with radiological fndings and to emphasize the effects of this situation on planned surgical proce -dures. A 62-year-old female patient had an interesting abnormality on the left collecting system, which wasrevealed on excretory urography (EU), retrograde urography (RU) and multidetector computed tomography(MDCT). A kinky left ureter, which formed a U shape, was revealed on EU. On MDCT, an accessory kidneywas revealed at the anterior aspect of the middle zone of left main kidney. The ureter of the main left kidneydrained directly into the accessory kidney. The course of this drainage was confrmed by retrograde urogra-phy. An accessory kidney is a rare entity associated with horseshoe kidney, ectopic ureter draining into thevagina, bifd collecting system and coarctation of the aorta. In our case, an unusual association between theureters of the main and accessory kidneys was revealed, which may have an impact on planned surgery inthe groin and retroperitoneal areas.