The transplant renal artery false aneurysm is a rare event but can be fatal. We report the case of a patient with a false aneurysm, which appeared 6 years after transplantation. The clinical presentation was an increase of the creatinine value and de novo graft hydronephrosis. The first ultrasound performed showed no aneurysm, leaving doubt whether this would not have been caused iatrogenically with the nephrostomy catheter placement. On the other hand, the resolution of hydronephrosis with aneurysmectomy leads us to believe that the aneurysm had existed previously. We consider this an interesting case by the manner of presentation and the success of the approach. A 44-year-old male patient received a first kidney transplant from a cadaveric donor in August 2005. Active bleeding was detected in the early post-operative period. He was reoperated and an arterial anastomotic dehiscence needing a vascular reconstruction was found. The remaining post-transplant period was unremarkable with a baseline serum creatinine of 2.0 mg/dL. In October 2011, he had an asymptomatic increase in serum creatinine to 2.7 mg/dL and urine analysis was completely normal. Ultrasonography showed a de novo hydronephrosis. Provisional diagnosis of obstruction was contemplated and a percutaneous nephrostomy was placed. Renal function did not improve. Ultrasonography was repeated showing a hypoechoic mass with a pulsatile flow pattern by colour Doppler scanning and maintained hydronephrosis. Subsequent computed tomography angiography confirmed a 4 × 4 cm false aneurysm at the anastomosis of the transplanted renal artery with the right external iliac extern (Figure 1). Digitally subtracted angiography was done prior to surgery (Figure 2). The resection of the false aneurysm was performed and the transplanted renal artery was anastomosed to the external iliac artery. Post-operatively, creatinine improved to basal value and ultrasonography showed no hydronephrosis. Fig. 1. Three dimensional computed tomography angiography reconstruction view showing the false aneurysm and the nephrostomy catheter. Fig. 2. Digitally subtracted angiography showing the false aneurysm at the junction of the transplanted renal artery with the right external iliac artery. False aneurysms following kidney transplantation are rare, but can be potentially devasting and cause functional impairment and even loss of the graft due to the risk of rupture [1]. Patients are usually asymptomatic and they are diagnosed incidentally. They can be managed conservatively with regular monitoring if the false aneurysms are small. When they cause clinical signs or risk rupture, interventional treatment is required.