The dramatic clinical consequences of anastomotic leakage in gastrointestinal surgery can be reduced by a diverting stoma or drainage of the peri-anastomotic area. Currently, the surgeons' clinical judgement is of major importance in decision making, but reliable data of the diagnostic accuracy are lacking. In this prospective clinical study, the surgeons' predictive accuracy for anastomotic leakage was evaluated. In 191 patients undergoing colorectal resection with anastomosis, the risk for anastomotic leakage was determined by the surgeon on the basis of a visual analogue scale (VAS). This risk assessment was compared to the actual occurrence of anastomotic leakage post-operatively. A total of 26 (13.6%) patients showed anastomotic leakage. The surgeons' median predicted leakage rate was 7.1% in anastomoses >15 cm from the anal verge and 9.5%