We report a case of transurethral resection of the prostate (TURP) syndrome with mild hyponatremia, severe lactic acidosis, and hypotension. A 73-year-old man with benign prostatic hyperplasia underwent monopolar TURP. Two episodes of hypotension occurred during the operation. These were corrected after injection of a bolus of ephedrine. After the operation, the hypotension persisted and lactic acidosis worsened. Abdominal distension was evident postoperatively. Abdominal ultrasound and computerized tomography revealed a large amount of fluid in the abdominal cavity. We suspected the leakage of sorbitol-containing irrigating fluid. After percutaneous drainage, the lactic acidosis resolved and hypotension stabilized.