Creeping woodsorrel (Oxalis corniculata) is a common weed found throughout Korea and is sometimes consumed as herbs. In the past, it has also been used as a drug as a folk remedy for cystitis. a 79-year-old female patient has a history of previous treatment for cystitis several times, and has no history of drug allergies. After hearing that Creeping woodsorrel was good for the prevention of cystitis, it was collected and consumed several times with green juice. After that, she visited the hospital due to general weakness and nausea. At the time of visiting, it was confirmed that serum creatinine was 4.58 mg/dL and BUN 91.9 mg/dL. CRP was 0.31 mg/dL. The urine test performed at the time of visiting showed pyuria. In the urine cytology test, less than 5 neutrophils, plasma cells, and eosinophils were found per HPF. In the 24-hour urine test, 301 mg of proteinuria was confirmed, and it was measured to be more than 51.5 mg of oxalic acid. In order to promote urinary elimination of oxalic acid, and disolve calcium oxalate crystals, oral citrate (urocitra-K SR 1080 mg tid) was administered with saline. After one week of the above measures, serum creatinine was improved to 1.72mg/dL, and oral water intake and citrate administration were maintained after discharge. The test performed at the outpatient clinic after 1 month confirmed that the renal function was completely recovered to 0.68mg/dL of creatinine. In the follow-up urine test, the findings were normal.This is a case showing that serious acute kidney injury occurs when plants with high oxalic acid are consumed in large quantities such as Star fruits and spinach.The patient recovered without dialysis with conservative treatment with appropriate fluid and oral citrate administration.