Setting A large training hospital in the Netherlands.Population Patients undergoing anterior colporrhaphy.Methods One hundred patients were included. Patients were randomised into two groups. In one group (n ¼ 50), a transurethral catheter was in place for four days post-operatively and removed on the fifth postoperative day. In the other group (n ¼ 50), catheterisation was not prolonged and the catheter was removed the morning after surgery. Residual volumes after removal of the catheter were measured by ultrasound scanning. Where residual volumes of >200 mL were found the patient was recatheterised for three more days. Urinary cultures were taken before removal of the catheter. Six patients were excluded: four in the standard prolonged catheterisation group and two in the not prolonged catheterisation group. Main outcome measures Need for recatheterisation, urinary tract infection, mean duration of catheterisation and hospital stay. Results Residual volumes exceeding 200 mL and need for recatheterisation occurred in 9% in the standard prolonged catheterisation group versus 40% of patients in the not prolonged catheterisation group (OR 0.15, 95% CI 0.045 -0.47). Positive urine cultures were found in 40% of cases in the standard prolonged catheterisation group compared with 4% in the not prolonged catheterisation group (OR 15, 95% CI 3.2 -68.6). Mean duration of catheterisation was 5.3 days in the standard prolonged catheterisation group and 2.3 days in the not prolonged catheterisation group (P < 0.001). Mean duration of hospitalisation was 7 days in the standard prolonged catheterisation group and 5.7 days in the not prolonged group (P < 0.001). Conclusion The disadvantages of prolonged catheterisation outweigh the advantages, therefore, removal of the catheter on the morning after surgery may be preferable and longer term catheterisation should only be undertaken where there are specific indications.