The double J stent provides a convenient means of drainage for the upper urinary tract. It is a common procedure in daily urologic practice. The indications of double J catheter placement include the relief of ureteral obstruction secondary to diverse etiologies, accommodating adequate postoperative drainage, and preventing ureteral injuries during surgical procedures. However, serious complications such as migration, fragmentation, encrustation, and stone formation still occur, especially when stents are left in place for long periods of time. Herein we report a case of a forgotten double J ureteral stent complicated by stone formation.