SUMMARY A series of investigations were undertaken to study urinary infections following transurethral surgery. These showed that closed catheter drainage achieved an infection rate of 5 per cent. Continuous saline irrigation did not reduce this rate and may even increase it, as did prolonged catheter drainage. Patients with small resections, short resection times and minimal blood loss had a smaller risk of becoming infected. Infections associated with prolonged catheter drainage, unlike those associated with irrigation, tended to persist even after discharge from hospital.