Introduction: The kidneys are generally spared in polymyositis. We report on a 57-year-old woman with Polymyositis presented rhabdomyolysis and myoglobinuria, as a result oliguric AKI which required hemodialysis. Case: 57-year-old woman visited with posterior neck pain and weakness in both extremities, decreased urine output and dark-colored urine. She had no strenuous exercise history, no alcohol or drug abuse history. Lab findings were increased serum creatinine (maximum 4 mg/dl), CK (5,369 IU/L) and Myoglobin (4,346 ng/ml). Tc-99m-MDP Bone scan shows slightly increased uptake in calf muscles with reserved urinary activity. After hydration and bed rest, patient’s renal impairment and muscle strength gradually improved. After discharge, she visited again with severe pain on both thighs and swelling on both upper arms, weakness on both extremities. Myoglobinuria, serum creatinine 4.4mg/dl, potassium 6.8 mEq/L, CK 50,470IU/L, Myoglobin 63,559 ng/ml, CK-MM 33,269 ng/ml, AST 1,238IU/L, ALT 647 IU/L, LDH 7,070 IU/L were observed. Muscle biopsy shows Polymyositis. EMG shows profuse fibrillations with sharp waves and low-voltage polyphasic units. Follow-up Tc-99m-MDP Bone scan demonstrated increased uptake in various muscles without urinary activity, suggesting AKI due to non-traumatic rhabdomyolysis. Hemodialysis was done due to oliguria and hyperkalemia didn’t respond to supportive care. After starting steroid therapy, symptoms gradually improved. Discussion: The patient was confirmed Polymyositis with muscle biopsy and the EMG. Usually, Polymyositis has a gradual progression and rarely presents as an acute episode. Fewer than 10 cases of Polymyositis-induced AKI have been reported, and it is uncommon for Polymyositis patients with AKI which requires hemodialysis. Early recognition and treatment is essential to minimize renal damage. In conclusion, diagnosis of Polymyositis (or Dermatomyositis) must be considered in patients with recurrent non-traumatic rhabdomyolysis and myoglobinuric AKI.