- Urolithiasis is an uncommon complication of renal transplantation, reported in approximately 0.5%–1% of renal allografts [1, 2, 3, 4, 5]. The risk factors are mainly hyperparathyroidism and non-absorbable sutures [2, 3, 6]. Other predisposing factors include ureteral obstruction, chronic urinary stasis, foreign body nidus (i.e., internal stents), metabolic diseases, and graft-gifted lithiasis (pre-existing stone in a donor kidney) [2, 4, 7, 8, 9]. The use of ureteral stents in renal transplantation may prevent ureteral complications related to the ureteroneocystostomy performed during transplantation . However, routine use of ureteral stents has been criticized, due to various stent-related problems including urinary tract infection, secondary obstruction, stent migration or breakage, stone formation and hematuria [8, 10]. If a stent is not used, the risk of a forgotten stent may also be eliminated, but this must not constitute a contraindication . Consequently, if stents are to be used during renal transplantation, documentation and follow-up are strongly recommended. We report a case of complete staghorn calculus and large bladder stone formation on a forgotten stent in a renal transplant patient. The case was successfully treated with percutaneous nephrolithotomy combined with cystolithotripsy.