A 63-year old male was referred to our emergency unit due to acute renal failure. The level of serum renal function tests levels, blood urea nitrogen (BUN)/creatinine, were 63 mmol/L/848 μmol/L. CT (Computarised Tomography) scan showed a huge bladder stone (5 cm x 6 cm x 5 cm) with increased bladder wall thickness. Post-renal acute renal failure due to bilateral ureterohydronephrosis was diagnosed. The huge bladder stone was considered to be the cause of ureterohydronephrosis and renal failure. The patient was catheterised and received haemodialysis immediately. He received haemodialysis four times during ten days of hospitalization and the level of serum renal function tests levels (BUN/ creatinine) decreased 18 mmol/L/123 μmol/L. After improvement of renal function, we performed cystoscopy that demonstrated normal prostatic urethra and bladder neck and bilaterally normal ureteral orifices. Bladder wall was roughly trabeculated and Bladder outlet was completely obstructed by a huge bladder stone. After cystoscopy open, cystolithotomy was performed to remove calcium phosphate and magnesium ammonium phosphate stone weighing 200 g removed. Four days after operation the patient was discharged uneventfully and urethral catheter was removed on the seventh day. Post-renal acute renal failure due to large bladder stones is rare in literature. According to the our knowledge; early diagnosis of the stone avoid growth to large size and prevent renal failure.