Transurethral resection is the most efficacious and safest urologic procedure for the treatment of benign prostatic hypertrophy, prostate cancer, and bladder cancer. Complications of transurethral resection include hemorrhage, infection, transurethral resection syndrome, and bladder perforation. Early detection of bladder perforation is important because it can cause critical ventilation and hemodynamic changes. In this case, we detected bladder perforation as the cause of ventilation and hemodynamic change intraoperatively and treated it by immediate surgical repair.